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Teachers manual science 8. Science 8 Teachers Guide

The water was cold. The energy was released from my hand to the water. Answers may vary, depending on how close the students answers are to the measured value Container 1 or the container that was added with hot water Container 3 or the container that was added with cold water The water added to the containers are of different temperatures.

Heat transfer was taking place in containers 1 and 2. There was a change in the temperature of water in these containers. Greater amount of heat was transferred in container 1. There was greater change in the temperature of water. The amount of heat transferred is proportional to the change in temperature. The greater the amount of heat transferred to an object, the greater the increase in its temperature. The aim of this activity is to explain why the temperature of water in Activity 1 increases when heat was added to it.

Also, by observing the behavior of the dye through the water, students will describe the effect of heat transferred to the particles of water. The greater the amount of heat transferred to an object, the greater the increase in the kinetic energy of the particles and the greater the increase in the temperature of the object.

At this point, students should be made to realize that everything is made up of moving particles. In Table 2, last column, students observations must focus on the scattering of the dye through the water. Ask them to make comparisons, like the dye scatters faster or slower or the dye scatters the most or the least. They will later relate these observations to the speed of the moving particles. At the end of the discussion, students should be able to recognize that hotness or coldness indicates how fast the particles move.

Hot may be considered as faster movement of the particles or higher kinetic energy of the particles. Observations Dye scattered the slowest Dye scattered slower than in hot water or faster than in cold water The dye scattered the fastest in this container. Answers to Questions Q9. After putting drops of dye into the water, the dye scattered throughout the water.

The rate of scattering of the dye differs in each container. Hot water. Cold water. The higher the temperature of the water, the faster the scattering of the dye. The particles are moving fastest in the container with hot water. The particles are moving slowest in the container with cold water. The higher the temperature of the water, the greater the speed of the moving particles.

The higher the temperature, the greater the kinetic energy of the particles. Thermal Expansion Explain how liquid thermometers work using the concept of thermal expansion. Demonstrate the activity described or suggested in the module to explain thermal expansion of solid. Emphasize that objects or materials expand when heated and contract when cooled.

But emphasize also that different materials expand or contract to different extents when heated or cooled. If time permits, ask the students to research more on the applications of thermal expansion to real life.

If the materials are available, some groups or students may be allowed to use a burner to heat the beaker of ice. Then let them compare their results and explain the difference in terms of the effect of the amount of heat absorbed by the ice to the time the ice takes to melt completely.

Students can be allowed to use an iron stand with clamp to hold the thermometer to ensure that it will not touch the bottom of the container. At this point, some guides in constructing graphs might be needed. Note that the independent variable heating time is plotted along the horizontal axis while the dependent variable temperature is plotted along the Y-axis.

Try out the activity first to determine the amount of ice that will allow the students to finish their activity on time. The ice melts because the heat from the surrounding higher temperature was absorbed by the ice lower temperature.

The dependent variable is the temperature while the independent variable is the time. Descriptions may vary depending on how the graphs of the students look like.

The accepted one should have a straight horizontal line like in the graph shown in Figure 2 below melting. The temperature of the water while the ice was melting remains the same. After the ice has melted the temperature of the water increases with time. The accepted one must have a straight horizontal line like in Fig.

Both graphs have a straight horizontal line but the temperature level corresponding to these lines differ. After students learned about the relationship between the temperature of the object and the amount of heat it can transfer, this time they will try to investigate on their own the relationship between the mass of the object and the amount heat it can transfer.

In this activity, students are asked to plan and design their own investigation, including the steps on how they will gather and analyze data to come up with an answer to this question: How does the mass of an object affect the amount of heat it can transfer? Example: Students may fill identical containers with different amounts of water of the same temperature, say hot water. Then they pour both contents into two containers with water of the same amount and temperature.

Then they measure the increase in temperature of water in both containers. The amount of increase in the temperature of water can be related to the amount of heat transferred to the object. Make sure that the liquid samples are stored in the same room before the experiment to ensure that they will be of the same room temperature when they are used in the activity.

Aside from water and cooking oil, other samples of liquids can also be used. If there are enough thermometers available, it is better to use a separate thermometer for each liquid sample. During the post activity discussion, provide the class with the table containing the specific heat capacities of some materials. This will confirm their findings that different materials have different heat capacities. During the post lab discussion, include some real life applications of specific heat capacity.

The water requires more time to increase in temperature. The water requires more heat to increase in temperature. The water has greater heat capacity. In the previous modules, students learn about charges and how their charges determine the forces that exist between them. In this module, they will study charges as moving through conducting materials.

Students will be dealing mostly on terms like voltage, current and resistance in studying electricity. In the first activity, they will determine how changing the voltage affects the current in an electric circuit.

The second activity deals with how resistance affects the current in a circuit. The next activity talks about the two types of connection series and parallel connections and how the charges flow in these connections.

The last activity of this module deals with the effects of too much current in the circuit on conducting materials, and how its effect can be useful in practicing safety practices in using electrical appliances in order to prevent accidents like fires or electric shock.

The topics covered in this module are relevant because of the applicability of the lesson in preventing accidents like fires caused by unsafe use of electricity. How do voltage and resistance affect electric current? What are the safety precautions needed in using electricity? Current and Voltage Electric charges can be made to move through a conducting material. The electric charges are the electrons of the conducting materials. Materials such as copper, steel, and aluminum have a lot of loosely held electrons which made them good conductors of electricity.

Current is a measure of the number of charges passing through a cross-section of a conductor in a given time. What is the direction of current? The movement of charges from the positive side of the battery to the negative side is called conventional current or simply current. However, this is not the actual motion of electrons in a circuit. The direction of the flow of electrons is from the negative terminal to the positive terminal.

This is called electron current. The direction of current does not affect what the current does. An ammeter measures electric current. Because the device measures how much charges flow in a certain cross section at a given time, it has to be connected in series. Take note how the positive and negative signs of the ammeter and the terminals of the battery are oriented as shown in Figure 1. Energy is needed to make the charges move.

In Module 2, the students learned that when work is done on an object, energy is transferred. The voltage of a battery does the work on charges to make them move.

Batteries are energy sources. The chemical energy in the battery is transformed to electrical energy. This electrical energy moves the charges in a circuit. The work done on the charges as it passes through a load is measured as the voltage across the load. A voltmeter measures voltage. The voltmeter must be connected parallel or across the load as shown in Figure 2.

The positive terminal of a voltmeter is connected to the positive terminal of the bulb while the negative terminal is connected to the negative terminal of the bulb as shown in Figure 2. In this activity, students will determine how voltage and current are related. Students will use voltmeters and ammeters to measure the current and voltage in a circuit.

Make sure that they follow the correct way of connecting the ammeter and voltmeter. If the school cannot provide voltmeters and ammeters, they can modify the activity by just relating the number of dry cellsor increase in voltage with the brightness of the bulb.

The brighter the bulb, the bigger the current. The dry cells must be connected in series which means the positive terminal of one cell is connected to the negative terminal of the other. Ideally a switch must be included in the circuit so that they can turn off the circuit to avoid wasting energy.

The teacher can make an improvised switch using illustration board and aluminum foil as shown in Figure 3. Be sure also to use new batteries for this activity especially when the brightness of the bulb is being asked. For the bulb, use a flashlight with a voltage rating of 2.

In case no battery holders, use a cardboard to wrap two batteries tightly like a cylindrical holder. Tape the cartolina to secure the tightness of the connection of the batteries. Answers to Questions: Q1. This will depend on the reading they get from the ammeter. The bulb glows brighter when two batteries are used. This will depend on the reading obtained in the ammeter. The current is higher for two dry cells as compared to one dry cell.

This will depend on the readings obtained on the voltmeter. The bulb glows brighter. The voltage is bigger for two dry cells as compared to one dry cell. For a constant load one bulb , when the voltage increases the current also increases.

Activity 1 Discussion The dry cell provides the energy that moves the charges in a circuit. The dry cell must be connected by conducting wires to a load to form a complete circuit. Adding dry cells in series increases the voltage in a circuit. In the activity, adding dry cells increases the current in a circuit as shown by the ammeter readings. The brightness of the bulb also indicates the amount of current passing through it.

The bigger the current through the bulb, the brighter it glows. Both the meter readings and the brightness of the bulb show that voltage and current are related. The activity shows that as the voltage increases, the current also increases.

Current and Resistance Another variable that can affect current is the resistance. As the term implies, the resistance of the material opposes the flow of charges. Resistance can also be measured and they are expressed in units called Ohms. A lower resistance would mean that there is less opposition in the flow of charges and therefore bigger current. Different materials have different amounts of resistance.

Conductors definitely have very little resistance and therefore allow more charges to pass through. Insulators are materials that have very high resistance and therefore flow of charges would be difficult.

The length and thickness of the conducting wire are factors that affect resistance encountered by current. The longer the wire the greater will be its resistance and the greater the cross sectional area a measure of the thickness of the wire , the lower will be its resistance.

The resistance of an object also changes when the object becomes wet. Dry human skin for instance has a resistance of , ohms but when it gets wet its resistance is reduced to 1, ohms. That is why it is important to dry the hands when plugging an electrical appliance to reduce any chance of getting a lot of current if an accident occurs. Understanding the relationship between current and resistance is important in protecting oneself from electric shock.

The table below shows the physiological effects that happen when a certain amount of current passes through the human body. In this activity, the students must be able to determine how resistance affects the current through the circuit. The purpose of the activity is to find if a relationship exists between current and resistance. If there is no ammeter available, the students can just compare the brightness of the bulb since the brightness is also associated with the current passing through them.

In the last part of the activity, the students were asked to connect the ammeter at different points in the circuit. This is to show to them that current is the same anywhere in the circuit. Answers to Question Q The current decreases as the resistance increases or when the resistance increases the current decreases. Sample data: No. The current reading at different points of the circuit is constant.

The readings indicate that current is the same anywhere in the circuit. In a series circuit, loads form a single pathway for charges to flow. A gap or a break anywhere in the path stops the flow of charges.

When one bulb is removed from the socket, a gap is created. The other bulb turns off as there is no longer current in the circuit. The total resistance in a series circuit is equal to the sum of the individual resistances of the load bulb.

Current is the same in every part of the circuit. The current is equal to the voltage divided by the total resistance.

As more load bulb is added in a series circuit, the smaller the current as reflected by the brightness of the bulb. The voltage across each load depends on the loads resistance. The sum of the voltage across each load is equal to the total voltage. Parallel connection Circuit B in Activity 3 is a parallel circuit.

In a parallel circuit, loads form branches; each provides a separate path for charges to flow. A gap or a break in any branch will not affect the other branches. Thus, when one bulb is removed from the socket, a gap is created only for that branch.

The other bulbs still glow as their path is still complete. In a parallel connection the voltage is the same across each load. The total current is equal to the sum of the currents in the branches. The amount of current is inversely proportional to the resistance of the load. In this activity students will find out how series and parallel connections are constructed. Giving them a situation to figure out how to do it stimulates problem solving skills of students. Be sure that when you let them do circuit A there should only be three wires for each group.

For circuit B only four wires should be given. If the number of wires is not limited, they will not be able to execute the simplest way to demonstrate connections of bulbs in series and parallel.

Tell the class to show them what they have constructed and check if it fits to the condition one bulb unscrewed, then other one turns off for Circuit A; one bulb is unscrewed and the other bulb remains lighted for Circuit B.

Usually the series connection is easier for the students. For parallel connections, students will experience some challenge in doing it. Most textbooks show parallel connections shown in Figure However, students might have another way of connecting the bulbs and these possible outputs shown below are also in parallel. Figure 5 Parallel circuits In the last part of the activity, the students were asked to measure the voltage across the two bulbs and the voltage drop across each bulb in circuits A and B.

Sample data is shown below: Table 3 Circuit. Circuit A shows that the voltage of the dry cell is divided between the two bulbs. The voltage depends on the resistance offered by the bulbs. If the bulbs are identical, the measurement should be the same. Circuit B shows that the voltage across each bulb is almost equal to the voltage of the dry cells. This shows that in this type of connection, voltage is the same across any two points in the circuit. Answers to Questions: Q There is only one path for current in Circuit A.

Because there is only one pathway for the current, when one bulb is removed from the holder, it made a gap or a break in the path. All bulbs connected will go out. There are two paths for current in Circuit B. Since only the path of the unscrewed bulb has the gap, the other bulb shines because its path is complete. The current can still pass in the path of the bulb with a complete pathway.

Circuit B has brighter bulbs. The current in Circuit A becomes smaller as more bulbs are added because the bulbs glow dimmer. The brightness of the bulbs in Circuit B remains the same as bulbs are added in the circuit. The current in Circuit B is bigger than in Circuit A. Safety in Using Electricity Fires can happen when the wires start heating up causing combustible parts of the house to be set on fire. The wires heat up when the current passing is more than what the wires can carry.

In this case there is an overloading of the circuit. An example of how the circuit gets overloaded is by plugging a lot of appliances in a common outlet like an extension cord. Another instance of overloading of the circuit is the presence of short circuits. Short circuits happen when wires with defective rubber insulation touch each other so the current does not pass to the supposed path it should take.

It is a circuit where the current encounters very little resistance and therefore the amount of current will increase rapidly. Such increase in the amount of current leads to the overloading of the circuit and can lead to fires. But why do wires heat up when there is too much current? In the wires the electrons that flow in a closed circuit collide with the atoms of the conducting wire. As the collisions take place the kinetic energy of the metal atoms increases.

The increased kinetic energy of the atoms is dissipated as heat. You learn in the module on heat that temperature is related to the kinetic energy of the moving particles. The higher the kinetic energy of the particles, the higher will be its temperature. The higher the current passing through the wire, the more collisions between the electrons and the atoms of the wire take place. In the end the wire will become hot. So just imagine how much heat will be generated from an overloaded circuit.

There are two tasks in Activity 4. The first part shows how increasing the current can cause the wires to heat up. The second task shows how a short circuit happens.

The fine copper wire to be used can be obtained from stranded electric wires. Remove the rubber insulation and get these fine copper wires for this activity.

Figure 6 Strands of copper wires The first task shows the wire heats up melting the candle. The hotter the wire the deeper will be the cut made on the candle. The second task is a simulation of a short circuit. Supervise the students making sure that they dont let touching of the exposed parts of the wire take too long as the wires get hotter afterwards.

The candle touching the wire melts. The current in the circuit increases. Heat is produced along the wire. The bigger the current in the circuit, the wire becomes hotter, and the more the candle will melt. The light goes off when the wires touch each other. The current took the path of the exposed part of the wire touching each other. The resistance encountered in the short circuit where the charges flowed is lower. The current in the short circuit increases. Short circuits cause fire when the nearby materials near the wires becomes so hot and starts to burn.

Resistance decreases as more appliances are connected to one outlet. The total current increases. Overloading the circuit can make the wires hot setting combustible materials on fire.

References and Links Henderson, Tom. This unit deals with the propagation of sound through solid, liquid, and gas.

In the course of discussion, wave characteristics and properties particularly reflection and refraction will be taken into account. From the activities, students will be able to identify also the factors that affect the speed of sound.

At the end of the unit, students should be able to: 1. Related Misconceptions 1. Sounds can be produced without using any material objects. Hitting an object harder changes the pitch of the sound produced. Sounds can travel through empty space a vacuum. Sounds cannot travel through liquids and solids. Sound travels slower in less dense medium. The greater the density of the medium the faster the sound is transmitted.

On which medium does sound travel fastest? Solid, Liquid, or Gas? How does the temperature of the medium affect the speed of sound? How are reflection and refraction manifested in sound? Facilitating Learning Motivation The facilitator may start with the popular songs of popular artists like maroon 5, Justin Bieber, and Taylor Swift. Students may be asked to sing some of the popular tunes and ask them who are fun of watching concerts?

Also ask them why concerts are usually done during night time and not during day time. Probe further until the concept of sound as a wave is deduced. Facilitating Learning Introduce Activity No. Since Activity No. Data processing may be done by group presentation and class discussion of the guide questions to probe the concept that sound waves are vibrations that travel through the air and that sound is transmitted in air through vibrations of air particles.

Discussion should also be extended to cover the differences and similarities of longitudinal and transverse waves and introduction to the characteristics of longitudinal waves. Then introduce Activity No. In this activity the students will use a metal slinky to 1 distinguish the different characteristics of waves; 2 determine the frequency and wavelength; and 3 compute the wave speed based on the frequency and wavelength.

Data processing may be done by group presentation. Class discussion of the data in tabular form and guide questions to the characteristics waves. Extend the discussion to emphasize that sound waves are also called pressure waves.

From here, introductory discussion on factors affecting sound may be included. In this activity the students should be able to distinguish which material transmits sound the best. Data processing may be done by group presentation and class discussion of the data and results in tabular form and guide questions to speed of sound in different media.

Extend the discussion to include characteristics of other media like solids and liquids then let them do worksheet 1 and Activity No. In this activity, they will have to design their own chime and use this chime to determine how density of the material or medium affects the speed of sound. Ask where does sound travel faster? In hotter medium or cooler medium? Introduce Activity No. In Hotter or Cooler? In this activity the students will be able to determine how temperature affects the speed of sound.

Extend the discussion to include calculation of the speed of sound with respect to the temperature of the medium. Let them do Worksheet No. Summarize Lesson 1 by going back to the key questions particularly questions 1 and 2. Use the question posted in the motivation to introduce the concept of properties of sound. Data processing may be done by group presentation and class discussion of the data and results in tabular form and guide questions to refraction and reflection of sound waves.

Extend the discussion to include practical application of sound reflection and refraction. Summary of the whole module may be probed by asking the 3rd key question and by asking for insights and experiences they had during the preparation, presentation and post-presentation discussion of their outputs.

In this activity, students will be able to infer that sound is KE of vibrations that travel through the air; and sound is transmitted in air through vibrations of air particles. The salt bounced up and down.

When the small can is tapped loudly or forcefully. Sound was produced when the small can is tapped. Yes the salt bounced up and down the plastic top while tapping the small can. The sound produced in the small can made the plastic top of the large can vibrate making the salt bounce up and down. Sound waves are vibrations of air particles. The rock salt bounced higher the loudness of the sound is increased. The amplitude of the wave.

The other colored beads collided with the blue bead. Yes Yes Sound wave is classified as a longitudinal wave. In this activity, students will be able to distinguish the different characteristics of waves; determine the frequency and wavelength; and compute the wave speed based on the frequency and wavelength.

Yes Yes. In this activity, students will be able to infer using improvised chimes that closely spaced particles of the medium are best transmitters of sound. Chime 3 The more closely distanced the stringed objects in the chime, the better the sound is transmitted. In this activity, students will be able to be able to determine how temperature affects the speed of sound. In this activity, students will be able to be able to observe how longitudinal waves reflect and refract. The compressions or rarefactions bounce off after hitting the wall No they are not found on the same positions Sound will also bounce off when it strikes a fixed end or the wall The frequency of the wave increases Increase in frequency of the sound is manifested as change in pitch Amplitude increases Louder sound is observed Faster waves.

This unit is concerned with the demonstration of understanding of the some properties and characteristics of light. Among the characteristics and properties of light, we focus on refraction and specifically dispersion of light. We will try to find out through simple activities on how light disperse to form the colors of light. We will also try to find the hierarchy of colors of light in terms of frequency, wavelength, and energy. The different activities provided in this module will make us realize the beauty of everything with light.

How are refraction and dispersion demonstrated in light? In the different colors of light, which is bent the most and the least? Why do we see spectacular events in the sky like rainbows, red sunset and blue sky? Activity 1: The Colors of the Rainbow The Colors of Light.. The students will be able to infer that white light is made up of many different colors of light and each of these colors of light bends differently. Activity 2: Red vs.

Blue Students will be able to infer that Violet light bends more than red light when dispersed; and Bending depends on the refractive index, frequency and energy of the color of light. Students able to infer that the energy of the colors of light increases as one goes towards the right side of the color spectrum and red light has the least energy and blue light has the most energy.

Activity 4: The Spectrum Wheel Students will be able to infer that light is composed of colors of light of different frequencies and wavelength; the frequencies of the colors of light are inversely proportional the wavelength; the product of frequency and wavelength of the color lights is a constant; and the arrangement of colors of light shows the hierarchy of the color of lights corresponding energy.

Activity 5: Scientific Explanations behind my Beliefs Students should be able to come up with a presentation of the scientific explanations of certain superstitious beliefs related to observable phenomena in the sky.

Motivation The facilitator may introduce a character named Roy G. Ask students whether they are familiar with the character. Ask them also if there is a connection between the character and the lessons. Ask the students if they could guess some information or concept from the name of the character.

If the students recognize the colors of light then ask key question no. Follow it up by the 1st 2 key questions. As a brief review, introduce the concept of apparent depth and the concept of refraction of light.

Have a recall of the equation for index of refraction. Introduce the concept of dispersion as a special kind of refraction. Let them perform Activity 1 which will give students more information about how. This activity is composed of two parts. One makes use of locally available materials while the other makes use of the standard materials like prism and artificial source of light. A comparison of the two may be highlighted during the discussion of results.

The facilitator may let the students present their outputs per group and processing be done after all the groups have presented by culling ideas and concepts from the presented data and probing students to arrive at the concept of colors of light. From the students outputs in Activity 1, the facilitator may ask why a certain hierarchy of colors of light is observed.

Then introduce Activity 2 and let the students perform the activity to determine which is really more bent: the red light or the violet light. This will be explicitly described by the students during the processing when they present their outputs which would include the relation of the bending and the index of refraction of the color of light. The facilitator may let the students present their outputs per group and processing be done after all the groups have presented by culling ideas and concepts from the presented data and probing students to arrive at the concept that blue is bent more or violet is bent more than red light.

Then ask the students which color of light gives the most energy. Let them predict red or violet light. Let them perform Activity 3. The facilitator may let the students present their outputs per group and processing be done after all the groups have presented by culling ideas and concepts from the presented data and probing students to arrive at the concept that blue or violet has the highest energy and red has the least. Ask the students on which other characteristics of color of light does energy of colors depend on to introduce Activity 4.

This activity was already done in Grade 7. The focus of the activity in Grade 7 was to identify the corresponding frequency and wavelength of the each color of light and the computation of the speed of each of the colors of light. This time the focus is on how energy relates to the frequency of the colors of light. From the given materials, students will be able to determine the relationship between frequency and the energy of the colors of light.

Then the facilitator may ask which is really more bent the red light or the violet light? Then ask them some inferences on how rainbows are formed.

Ask them also some superstitious beliefs that the students are familiar of related to the existence of rainbows. Let them identify all the major concepts they were able to grasp from activity nos.

Then let them do Activity 5. Let the students present their outputs per group. Then go back to the key questions to be able to summarize the concepts on visible light. This causes the different colors of light to be refracted differently. Then leave the prism at different angles, creating an effect similar to a rainbow Some colors visible in the prism were not observed in the water Small value for refractive index is observed in red and large refractive index for red The refractive indices of the different color of light indicate that light of different colors travels at different speeds in the prism which accounts for the different amounts of bending.

Thus, blue light with greater refractive index refracts more and appears at the bottom of the red light. The wavelength decreases from red to violet while the frequency increases from red to violet.

White light separates into color light because it refracts with different refractive indices while passing through a medium like a prism. YES As the frequency of the color of light increase, the energy also increases. Red has the least frequency with the least energy and Violet has the highest frequency and the highest energy. The higher the frequency of the color of light, the greater is its energy. References Hewitt, Paul.

Conceptual physics 6th Ed. As in the previous grade, there will be three modules in this quarter: Module 1 is about Earthquakes and Faults. In Module 1, we continue to emphasize the idea that our location on the globe is intertwined with what we experience in our daily lives. For instance, the Philippines is located along the Ring of Fire. This means that earthquakes and volcanic eruptions are normal occurrences in our country.

We share the same fate with other countries that surround the Pacific Ocean, including Indonesia to the south and Japan to the north. They too have faults in their land where energy is locked for some time before it is unleashed in devastating earthquakes. Similar to our two neighboring countries, we are surrounded by the sea. And whenever the seafloor is suddenly jolted by a strong earthquake, a tsunami is generated and our coastal areas are swamped with deadly waves.

Mindanao and Mindoro have been victims in the not-so-distant past. In Module 2, we find out why we are prone to typhoons, too. In fact, The Philippines is hit by about 20 tropical cyclones each year. This number is an average, so sometimes we get more than that. What conditions in the vicinity of our country favor the formation of tropical cyclones?

Our country is located near the equator, surrounded by bodies of water. This combination means there is heat to warm up the waters of the ocean and produce a lot of water vapor. The rising warm air will soon turn into a lowpressure area that may intensify into a tropical cyclone. If only the Philippines were at a higher latitude, it would suffer less tropical cyclones because the surrounding waters would be colder. Or if the Philippines were at the equator, it would likely be free of tropical cyclones because there is no Coriolis force to make the air spin.

Or if only there was a landmass in the way that would dull the edge of a tropical cyclone that came in from the Pacific. Alas, there is no such luck. The Philippines is located right where tropical cyclones form and there is nothing to do but learn how to survive their annual onslaught. In Module 3, we will take up comets, asteroids, and meteors.

Luckily, the Philippines is not a favored target. But even without a direct hit, everyone will be affected if a really large chunk of rock came crashing from outer space. The last time that happened, it ended the reign of the dinosaurs.

So studying these foreign objects may pay off in the long run. In Grade 7, the students learned that the Philippines is one of the countries located along the Ring of Fire. The Ring of Fire refers to the region around the Pacific Ocean that are commonly hit by earthquakes and volcanic eruptions. Earthquakes will be covered in this grade level while volcanic eruptions will be tackled in the next. Every now and then, a strong earthquake hits the Philippines, leading to numerous deaths and widespread destruction.

We cannot stop this natural event from occurring. And up to now, scientists have not found a way to predict when an earthquake will occur. Thus, students must learn about earthquakes in order to survive. What is a Fault? Earthquakes occur when rocks along a fault suddenly move. The first thing to do then is to learn what a fault is.

A fault is a break in the Earths crust along which significant movement has taken place. Let us go through the definition in more detail. The word break refers to a crack in the ground. The word crust refers to the outermost layer of the Earth. We live on the surface of the crust. Significant movement means that the rocks have been displaced or shifted considerably.

Activity 1 is short and easy to do. All that is needed are sand and two pieces of cardboard and the students are ready to go. Tell the students to work on top of the newspaper to avoid sand spilling everywhere. The activity is supposed to simulate what the ground looks like as rocks move along a fault. Figure 1A is the starting point. Lay the two sheets side to side. Make the sand top flat so everything can be seen clearly. The two parallel lines are there so that the displacement will be obvious to the observer.

Figure 1B, C, and D shows how a crack forms in the sand. Figure 1A-D. Sheets are moved in the direction shown by the arrows. A crack forms in the sand and the lines are displaced. Before doing this activity, experiment with sand of different sizes. If the sand size is too big, the expected crack in the sand may not form or may be hard to see.

Look at Figure 1B, C and D. See the crack that goes from left to right? The students are supposed to see that.

After the activity, direct the students to Figure 4 in the student module. This is Figure 2 in this guide. Ask the students to compare what they saw in the activity to what is shown in the picture. The students are supposed to see that the crack in the sand is similar to the break across the road in the picture. You can then tell them that that is how a fault may look out in the field.

Figure 2. Answers to questions Q1. As you move the sheets, what is formed in the sand? Answer: A crack, line or break is formed in the sand. What happens to the lines? Answer: The lines are shifted or displaced. For advanced classes In Activity 1, the movement along the fault is in the horizontal direction.

That is, the ground moves sideways. You can also demonstrate movement in the vertical direction. The ground will be observed to move up or down.

All that is needed is sand and a narrow box cover. Get the box cover and cut it so that the length of one piece is twice the other Figure 3. If you cannot find a box cover, make one using cardboard.

Place the shorter box cover within the longer one Figure 4, left photo. Put sand in the nested box covers. Shake the box side to side so the surface of the sand will become level Figure 4, right photo. Figure 4. Left The short box cover is put within the long box cover. Right Sand is poured into the nested covers. Now, slowly pull the sides of the box covers as shown in Figure 5. Ask the students to observe carefully.

As you can see in Figure 6, two parallel cracks form in the sand. If you continue to pull, the sand in the middle of the cracks will subside move down , forming a depression.

This simulates what happens when the ground is pulled apart by forces within the Earth. Faults form, a portion of the land sinks, and a valley is formed. Figure 6. Left As the box covers are pulled outward, cracks form in the sand.

Right With more outward pulling, the sand subsides. Now, re-assemble the box covers as before. Do not forget to make the surface of the sand flat. This time, push the sides of the box covers toward each other Figure 7. Let the students observe what happens. As can be seen from Figure 8, the opposite happens. Instead of the sand sinking, the sand forms a tiny ridge. Unfortunately, this model does not show a crack in the sand that would represent a fault.

In the real world, a fault is formed when the ground is squeezed by forces from inside the Earth. A portion of the land is pushed up, and mountains are formed.

Note: Use fine sand when performing this demonstration. Coarse sand does not work as well. Experiment using different materials. How do faults produce quakes? Now that students have an idea of how faults look, let us show them how earthquakes occur along faults. To answer this question, the students will perform two short activities. In this activity, two small boxes are needed. The cartons that fruit juice drinks are packaged in are perfect.

Setting it up is simple Figure 9, left photo. The activity can be performed in groups, or as a class demo if you are pressed for time. The activity is supposed to show the sudden jerk that occurs when rocks move along a fault in an earthquake. The students may find it tricky to attach the rubber band to the box. Just punch two holes in the box, close enough so you can loop a paper clip or a thin wire through them.

Then attach the rubber band to the clip. Look at the photos in Figure 9 so you know how it should be done. The student is supposed to pull on the rubber band attached to one box while holding the other box in place. The rubber band should be pulled forward and horizontally, not sidewise, upward or downward. Expected result: The box will not move at first because it is taped to the other box which is being held. The rubber band will stretch.

The tape will suddenly come off. The box attached to the rubber band will jerk forward and the house will topple over Figure 9, right photo. This simulates the sudden movement that occurs along a fault. The success of this activity depends on the tape, which represents friction in real life.

If it is too sticky, the tape will never come off, no matter how much the rubber band is pulled. Tape it on just enough for the rubber to stretch a bit before the box jerks free from the tape.

In real world terms, this is what happens. Energy from inside the Earth exert a force on the rocks along faults.

But the rocks do not move right away because of friction. The roughness of the rocks keeps them from slipping past each other. But when the limit is reached, the rocks suddenly slipearthquake! Answers to Questions Q3. What happens to the rubber band? Answer: The rubber band stretches. What happens to the box attached to the rubber band? Answer: The box jerks forward. What happens to the house?

The house falls over. Which is the fault in this setup? The fault is the boundary between the two boxes. While Activity 2 simulates the sudden movement along a fault, it does not show the shaking that accompanies the sudden movement.

The increase in length of each strip from one strip to another is of equal size. This indicates equal changes in the velocity of the cart at equal periods of time when the force acting on it is constant. Yes, this is also true with the other tape charts.

The increase in length of the strips varies among the four tape charts. The amount of change increases as the units of force increases.

When the dots on top of the strips are connected, a straight line was formed. Yes, the same pattern exists for the other tape charts. The computed values of vave are increasing. This means that the cart is accelerating uniformly or its acceleration is constant.

The computed values of acceleration are equal or almost equal. The acceleration of the cart increases with the net or unbalanced force applied on it. Or as the amount of force applied on the cart increases, the acceleration of the cart also increases. The Newton's third law of motion, or sometimes called as Law of Action- Reaction, describes the relationship between the forces that two bodies exert on each other.

In this activity, students should realize that these forces are equal in magnitude but opposite in direction. Emphasize that this pair of forces are acting on different bodies, so they do not cancel each other out. Answers to Questions Q The forces that we exerted are in opposite directions. The readings this time should be greater than the previous ones Q We increased the force that we exerted on each other.

The forces are of opposite directions. Action-reaction Activity 5 Quezon City Acceleration 1 2 3 4 50 0 0 0 Force Figure 4: Graph of force vs acceleration The concept of energy is one of the most important concepts in physics. The students have been studying about it since Grade 3 up to Grade 7.

They have learned that energy takes many forms; there are different sources and uses of energy; and energy can be transferred. The module starts with a discussion about work.

In the first activity, they will explain whether a situation represents an example of work. It is followed by a discussion about work and energy, and then about kinetic and potential energy. The last activity puts together the concepts of work, energy and power. Key questions for this module What is work? Ask the students to identify the one doing the work and on which object the work is done. The students should be able to arrive at the concept that work is done on an object when the force applied to it covers a distance in the direction of the applied force.

What is work? What is energy? How are work, energy and power related? For them to explain if the situations represent examples of work they should be able to identify the one doing the work and on which object the work is done.

They should also look into the direction of force exerted relative to the direction of the movement of the object or the distance covered by the applied force. Teaching Tips 1. Let them look for the meaning of work in a dictionary. Recall the lesson about force in Module 1.

Yes, the situation is an example of work. The work is done by the girl on the cart. The force exerted by the girl in pulling the toy car is in the same direction as the distance covered when the force is applied. The work is done by the man on the box. The force exerted by the man is upward and the box is displaced upward. No, the situation is not an example of work.

There is force the shoulder pushes up the bag and there is displacement the bag is moved horizontally. However, the line of action of the force and the displacement are not parallel but perpendicular. The distance covered is not along the direction of the applied force. Is there work done? Activity 1 The work is done by the force of gravity on the mango.

In this case, the mango loses energy as you will find out in the discussion of potential energy. Calculating work The students are given the equation of work in their module. However, the equation can only be used if the force is applied horizontally pushed across the floor or ground or vertically lifted above. Figure 1. Equation for solving work The equation of work for forces at an angle is not introduced to the students because they have not yet taken up trigonometric functions in their mathematics class.

However, if the students ask how to solve for work if the force is at an angle, you may also show the equation. Figure 2. Equation for solving work if the force is at an angle d force d force force If the book is lifted from the floor to the top shelf which is 2 meters from the floor, how much work is done?

This time, they will learn that work is a means of transferring energy from one object to another. The energy became energy of motion of the ball. A moving ball has energy. When it strikes the empty plastic bottle, it can push it through a distance. Thus, work is done by the ball on the empty plastic bottle. Since work is done on the bottle, energy is transferred to it.

The one doing the work loses energy and the object on which work is done gains energy. When work is done by an object, the object loses energy; when work is done on an object, the object gains energy. In the bowling game the students played, the one rolling the ball loses energy while the ball gains energy. When the moving ball strikes the empty plastic bottle it loses energy while the plastic bottle gains energy.

What will happen to the KE of an object if its mass is doubled but the velocity remains the same? The KE will be doubled. How about if the velocity is doubled but the mass remains the same? The KE is proportional to the square of the speed, thus if the speed is doubled, the KE will be quadrupled. Potential Energy Work is done in lifting an object. When work is done on an object, energy is transferred to it.

Thus, an object lifted from the ground gains energy. Since the work is done against the force of gravity, it is called gravitational potential energy or simply potential energy PE. The force of gravity also acts on objects falling to the ground. As an object falls, the potential energy decreases because it is transformed to become the kinetic energy of the object. This energy depends on the mass and height of the object. The height can be measured relative to an assigned level.

But usually, the common reference level is the ground. Point out that the higher the object is from the ground, the greater is its potential energy. The more massive an object is, the greater is its potential energy.

These concepts were demonstrated in the problems. Answer to the problem: If the same 1. This way the students cannot see the mechanism inside the can. Rotate the barbecue stick beforehand before asking them what they think will happen to the can when placed on the floor. Answers to the questions: Q1. It rolls. Potential energy Q3. Kinetic energy Q4. Potential to kinetic energy Work, Energy and Power People possess energy. They get their energy from the food they eat.

As shown and demonstrated in the previous lesson, this energy can be transferred to objects. When people do things such as walking or running, they expend energy. The rate at which they expend energy is called power. Power is the rate of doing work or the rate of using energy. Rolling toy Activity 2 Troy Q6. Mae Q8.

Activity 3 Each member performed different amounts of work except for Bella and Elijah who performed the same amount of work because they weigh the same. Power output is determined by the amount of work done or energy expended and the time taken to do the work.

Summary Below is a list of concepts or ideas developed in this module. Conceptual physics. Saddle River, New Jersey. Kirkpatrick, L. Physics a world view.

Inquiry into Physics. Science and Technology IV. SEDP Series. Philippines: Book Media Press, Inc. This time, they will explore what happens to the object when heat is transferred to or from it.

They will also learn about the factors that affect the amount of heat that an object can transfer. Students are also expected to understand the difference between heat and temperature. Furthermore, this module hopes to address the following misconceptions on heat and temperature: 1.

Heat is a substance. Heat is not energy. Heat and temperature are one and the same. The temperature of an object depends on its size or volume. The amount of heat transferred is determined always by the change in temperature. The experiments were made simple so that students will be able to finish them early and the discussion of the results can be done also on the same day. What happens to solids, liquids, or gases when they absorb or release heat?

Does heat affect all kinds of materials in the same way? Are heat and temperature one and the same? They will also compare the amount of heat transferred to the water in terms of the changes in its temperature and describe the relationship between these two variables.

Since this is just a review of their previous lessons, students may be allowed to discuss their answers within their group.

Heat was transferred from my finger higher temperature to the cold water lower temperature. The water was cold. The energy was released from my hand to the water. Container 1 or the container that was added with hot water Container 3 or the container that was added with cold water Q5. The water added to the containers are of different temperatures. Heat transfer was taking place in containers 1 and 2. There was a change in the temperature of water in these containers.

Greater amount of heat was transferred in container 1. There was greater change in the temperature of water. The amount of heat transferred is proportional to the change in temperature. The greater the amount of heat transferred to an object, the greater the increase in its temperature.

The aim of this activity is to explain why the temperature of water in Activity 1 increases when heat was added to it. Also, by observing the behavior of the dye through the water, students will describe the effect of heat transferred to the particles of water.

The greater the amount of heat transferred to an object, the greater the increase in the kinetic energy of the particles and the greater the increase in the temperature of the object. At this point, students should be made to realize that everything is made up of moving particles.

Dye in water Activity 2 Ask them to make comparisons, like the dye scatters faster or slower or the dye scatters the most or the least.

They will later relate these observations to the speed of the moving particles. Sample data for Table 2: Container Temperature 0 C Observations Container 1 cold 12 0 C Dye scattered the slowest Container 2 tap 26 0 C Dye scattered slower than in hot water or faster than in cold water Container 3 hot 76 0 C The dye scattered the fastest in this container Figure 1.

Scattering of the dye among the three water samples Answers to Questions Q9. After putting drops of dye into the water, the dye scattered throughout the water. The rate of scattering of the dye differs in each container. Hot water. Cold water.

Cold waterWater at room temp Hot water The higher the temperature of the water, the faster the scattering of the dye. The particles are moving fastest in the container with hot water. The particles are moving slowest in the container with cold water. The higher the temperature of the water, the greater the speed of the moving particles. The higher the temperature, the greater the kinetic energy of the particles.

But emphasize also that different materials expand or contract to different extents when heated or cooled. Phase Change Teaching Tips 1. If the materials are available, some groups or students may be allowed to use a burner to heat the beaker of ice.

Then let them compare their results and explain the difference in terms of the effect of the amount of heat absorbed by the ice to the time the ice takes to melt completely. What happens when ice melts? Activity 3. Students can be allowed to use an iron stand with clamp to hold the thermometer to ensure that it will not touch the bottom of the container.

At this point, some guides in constructing graphs might be needed. Note that the independent variable heating time is plotted along the horizontal axis while the dependent variable temperature is plotted along the Y-axis. Try out the activity first to determine the amount of ice that will allow the students to finish their activity on time. The ice melts because the heat from the surrounding higher temperature was absorbed by the ice lower temperature. Descriptions may vary depending on how the graphs of the students look like.

The accepted one should have a straight horizontal line like in the graph shown in Figure 2 below melting. The temperature of the water while the ice was melting remains the same.

After the ice has melted the temperature of the water increases with time. The accepted one must have a straight horizontal line like in Fig. Both graphs have a straight horizontal line but the temperature level corresponding to these lines differ. After students learned about the relationship between the temperature of the object and the amount of heat it can transfer, this time they will try to investigate on their own the relationship between the mass of the object and the amount heat it can transfer.

Example: Students may fill identical containers with different amounts of water of the same temperature, say hot water. Then they pour both contents into two containers with water of the same amount and temperature. Then they measure the increase in temperature of water in both containers. The amount of increase in the temperature of water can be related to the amount of heat transferred to the object.

What is the relationship between the mass of a material and the amount of heat it can transfer? Activity 4 What happens to the temperature of water as it boils? Make sure that the liquid samples are stored in the same room before the experiment to ensure that they will be of the same room temperature when they are used in the activity. Aside from water and cooking oil, other samples of liquids can also be used.

If there are enough thermometers available, it is better to use a separate thermometer for each liquid sample. During the post activity discussion, provide the class with the table containing the specific heat capacities of some materials. This will confirm their findings that different materials have different heat capacities. During the post lab discussion, include some real life applications of specific heat capacity.

The water requires more time to increase in temperature. The water requires more heat to increase in temperature. The water has greater heat capacity. What are the safety precautions needed in using electricity?

In this module, they will study charges as moving through conducting materials. Students will be dealing mostly on terms like voltage, current and resistance in studying electricity.

In the first activity, they will determine how changing the voltage affects the current in an electric circuit. The second activity deals with how resistance affects the current in a circuit. The next activity talks about the two types of connection series and parallel connections and how the charges flow in these connections.

The topics covered in this module are relevant because of the applicability of the lesson in preventing accidents like fires caused by unsafe use of electricity.

The electric charges are the electrons of the conducting materials. Materials such as copper, steel, and aluminum have a lot of loosely held electrons which made them good conductors of electricity. Current is a measure of the number of charges passing through a cross-section of a conductor in a given time. What is the direction of current? The movement of charges from the positive side of the battery to the negative side is called conventional current or simply current.

However, this is not the actual motion of electrons in a circuit. The direction of the flow of electrons is from the negative terminal to the positive terminal. This is called electron current. The direction of current does not affect what the current does.

An ammeter measures electric current. Because the device measures how much charges flow in a certain cross section at a given time, it has to be connected in series. Take note how the positive and negative signs of the ammeter and the terminals of the battery are oriented as shown in Figure 1. Ammeter connected in a circuit Energy is needed to make the charges move. In Module 2, the students learned that when work is done on an object, energy is transferred.

The voltage of a battery does the work on charges to make them move. Batteries are energy sources. The chemical energy in the battery is transformed to electrical energy. This electrical energy moves the charges in a circuit. The work done on the charges as it passes through a load is measured as the voltage across the load. The voltmeter must be connected parallel or across the load as shown in Figure 2. The positive terminal of a voltmeter is connected to the positive terminal of the bulb while the negative terminal is connected to the negative terminal of the bulb as shown in Figure 2.

The teacher can make an improvised switch using illustration board and aluminum foil as shown in Figure 3. Current and voltage Activity 1 positive terminal of the bulb negative terminal of the bulb For the bulb, use a flashlight with a voltage rating of 2.

Tape the cartolina to secure the tightness of the connection of the batteries. Answers to Questions: Q1. This will depend on the reading they get from the ammeter. The bulb glows brighter when two batteries are used. This will depend on the reading obtained in the ammeter. The current is higher for two dry cells as compared to one dry cell. This will depend on the readings obtained on the voltmeter. The bulb glows brighter. The voltage is bigger for two dry cells as compared to one dry cell.

For a constant load one bulb , when the voltage increases the current also increases. The dry cell must be connected by conducting wires to a load to form a complete circuit.

Adding dry cells in series increases the voltage in a circuit. In the activity, adding dry cells increases the current in a circuit as shown by the ammeter readings.

The brightness of the bulb also indicates the amount of current passing through it. The bigger the current through the bulb, the brighter it glows. Both the meter readings and the brightness of the bulb show that voltage and current are related. The activity shows that as the voltage increases, the current also increases. Current and Resistance Another variable that can affect current is the resistance. As the term implies, the resistance of the material opposes the flow of charges.

Resistance can also be measured and they are expressed in units called Ohms. A lower resistance would mean that there is less opposition in the flow of charges and therefore bigger current. Different materials have different amounts of resistance. Conductors definitely have very little resistance and therefore allow more charges to pass through.

Insulators are materials that have very high resistance and therefore flow of charges would be difficult. The length and thickness of the conducting wire are factors that affect resistance encountered by current.

The longer the wire the greater will be its resistance and the greater the cross sectional area a measure of the thickness of the wire , the lower will be its resistance.

Dry human skin for instance has a resistance of , ohms but when it gets wet its resistance is reduced to 1, ohms. That is why it is important to dry the hands when plugging an electrical appliance to reduce any chance of getting a lot of current if an accident occurs. Understanding the relationship between current and resistance is important in protecting oneself from electric shock.

The table below shows the physiological effects that happen when a certain amount of current passes through the human body. Source: Department of Health and Human Services, Center for Disease Control and National Institute for Occupational Safety and Health In this activity, the students must be able to determine how resistance affects the current through the circuit.

Current and resistance Activity 2 This is to show to them that current is the same anywhere in the circuit. Answers to Question Q The current decreases as the resistance increases or when the resistance increases the current decreases.

Sample data: Q The current reading at different points of the circuit is constant. The readings indicate that current is the same anywhere in the circuit. In a series circuit, loads form a single pathway for charges to flow. A gap or a break anywhere in the path stops the flow of charges. When one bulb is removed from the socket, a gap is created.

The other bulb turns off as there is no longer current in the circuit. Current is the same in every part of the circuit. The current is equal to the voltage divided by the total resistance. As more load bulb is added in a series circuit, the smaller the current as reflected by the brightness of the bulb.

The sum of the voltage across each load is equal to the total voltage. Parallel connection Circuit B in Activity 3 is a parallel circuit. In a parallel circuit, loads form branches; each provides a separate path for charges to flow.

A gap or a break in any branch will not affect the other branches. Thus, when one bulb is removed from the socket, a gap is created only for that branch. The other bulbs still glow as their path is still complete. In a parallel connection the voltage is the same across each load. The total current is equal to the sum of the currents in the branches. The amount of current is inversely proportional to the resistance of the load.

Giving them a situation to figure out how to do it stimulates problem solving skills of students. For circuit B only four wires should be given. If the number of wires is not limited, they will not be able to execute the simplest way to demonstrate connections of bulbs in series and parallel. Usually the series connection is easier for the students. For parallel connections, students will experience some challenge in doing it.

The voltage depends on the resistance offered by the bulbs. If the bulbs are identical, the measurement should be the same. Circuit B shows that the voltage across each bulb is almost equal to the voltage of the dry cells.

This shows that in this type of connection, voltage is the same across any two points in the circuit. Answers to Questions: Q There is only one path for current in Circuit A. Because there is only one pathway for the current, when one bulb is removed from the holder, it made a gap or a break in the path. All bulbs connected will go out. There are two paths for current in Circuit B. Since only the path of the unscrewed bulb has the gap, the other bulb shines because its path is complete.

The current can still pass in the path of the bulb with a complete pathway. Circuit B has brighter bulbs. The current in Circuit A becomes smaller as more bulbs are added because the bulbs glow dimmer.

The brightness of the bulbs in Circuit B remains the same as bulbs are added in the circuit. The current in Circuit B is bigger than in Circuit A.

Safety in Using Electricity Fires can happen when the wires start heating up causing combustible parts of the house to be set on fire. The wires heat up when the current passing is more than what the wires can carry.

It is a circuit where the current encounters very little resistance and therefore the amount of current will increase rapidly. Such increase in the amount of current leads to the overloading of the circuit and can lead to fires. In the wires the electrons that flow in a closed circuit collide with the atoms of the conducting wire.

As the collisions take place the kinetic energy of the metal atoms increases. The increased kinetic energy of the atoms is dissipated as heat. You learn in the module on heat that temperature is related to the kinetic energy of the moving particles. The higher the kinetic energy of the particles, the higher will be its temperature.

The higher the current passing through the wire, the more collisions between the electrons and the atoms of the wire take place. In the end the wire will become hot. So just imagine how much heat will be generated from an overloaded circuit.

The first part shows how increasing the current can cause the wires to heat up. The second task shows how a short circuit happens. The hotter the wire the deeper will be the cut made on the candle. Stay safe! Activity 4 The candle touching the wire melts. The current in the circuit increases. Heat is produced along the wire. The bigger the current in the circuit, the wire becomes hotter, and the more the candle will melt.

The light goes off when the wires touch each other. The current took the path of the exposed part of the wire touching each other. The resistance encountered in the short circuit where the charges flowed is lower. The current in the short circuit increases. Short circuits cause fire when the nearby materials near the wires becomes so hot and starts to burn. Resistance decreases as more appliances are connected to one outlet.

The total current increases. Overloading the circuit can make the wires hot setting combustible materials on fire. References and Links Henderson, Tom. In the course of discussion, wave characteristics and properties particularly reflection and refraction will be taken into account. From the activities, students will be able to identify also the factors that affect the speed of sound. At the end of the unit, students should be able to: 1. Sounds can be produced without using any material objects.

Hitting an object harder changes the pitch of the sound produced. Sounds can travel through empty space a vacuum. Sounds cannot travel through liquids and solids. Sound travels slower in less dense medium. The greater the density of the medium the faster the sound is transmitted. Related Misconceptions Solid, Liquid, or Gas? How does the temperature of the medium affect the speed of sound? How are reflection and refraction manifested in sound?

Students may be asked to sing some of the popular tunes and ask them who are fun of watching concerts? Also ask them why concerts are usually done during night time and not during day time. Probe further until the concept of sound as a wave is deduced. In this activity the students will use a metal slinky to 1 distinguish the different characteristics of waves; 2 determine the frequency and wavelength; and 3 compute the wave speed based on the frequency and wavelength.

Class discussion of the data in tabular form and guide questions to the characteristics waves. From here, introductory discussion on factors affecting sound may be included. In this activity the students should be able to distinguish which material transmits sound the best. In this activity, they will have to design their own chime and use this chime to determine how density of the material or medium affects the speed of sound. In hotter medium or cooler medium?

Introduce Activity No. In Hotter or Cooler? In this activity the students will be able to determine how temperature affects the speed of sound. Let them do Worksheet No. Then introduce Activity No. The salt bounced up and down. When the small can is tapped loudly or forcefully. Sound was produced when the small can is tapped.

Yes the salt bounced up and down the plastic top while tapping the small can. The sound produced in the small can made the plastic top of the large can vibrate making the salt bounce up and down.

Sound waves are vibrations of air particles. The rock salt bounced higher the loudness of the sound is increased. The amplitude of the wave. The other colored beads collided with the blue bead. Yes Q Sound wave is classified as a longitudinal wave. In this activity, students will be able to distinguish the different characteristics of waves; determine the frequency and wavelength; and compute the wave speed based on the frequency and wavelength Characteristics of waves: Comparing longitudinal and transverse waves Activity 2 The dancing salt and the moving beads!

Yes In this activity, students will be able to infer using improvised chimes that closely spaced particles of the medium are best transmitters of sound. Chime 2 Q Chime 2 Chimes Activity 4 Sound race Where does sound travel fastest? Chime 3 Q The chime with packed string objects produces sound that reached the farthest distance. The more closely distanced the stringed objects in the chime, the better the sound is transmitted. In this activity, students will be able to be able to determine how temperature affects the speed of sound.

HOT cylinder Q The higher the temperature, the faster the sound travels. In this activity, students will be able to be able to observe how longitudinal waves reflect and refract.

Reflecting and refracting sound Activity 6 Faster sound In hotter or cooler? Activity 5 The compressions or rarefactions bounce off after hitting the wall Q No they are not found on the same positions Q Sound will also bounce off when it strikes a fixed end or the wall Q The frequency of the wave increases Q Increase in frequency of the sound is manifested as change in pitch Q Amplitude increases Q Louder sound is observed Q Among the characteristics and properties of light, we focus on refraction and specifically dispersion of light.

The different activities provided in this module will make us realize the beauty of everything with light. Key questions for this module How are refraction and dispersion demonstrated in light? In the different colors of light, which is bent the most and the least? Why do we see spectacular events in the sky like rainbows, red sunset and blue sky? The Colors of Light.. The students will be able to infer that white light is made up of many different colors of light and each of these colors of light bends differently.

Ask students whether they are familiar with the character. Ask them also if there is a connection between the character and the lessons. Ask the students if they could guess some information or concept from the name of the character.

If the students recognize the colors of light then ask key question no. Follow it up by the 1st 2 key questions. Have a recall of the equation for index of refraction and let them do Activity No.

Let them perform Activity no. This activity is composed of two parts. One makes use of locally available materials while the other makes use of the standard materials like prism and artificial source of light. A comparison of the two may be highlighted during the discussion of results. This will be explicitly described by the students during the processing when they present their outputs which would include the relation of the bending and the index of refraction of the color of light.

Let them predict — red or violet light. Let them perform Activity No. The facilitator may let the students present their outputs per group and processing be done after all the groups have presented by culling ideas and concepts from the presented data and probing students to arrive at the concept that blue or violet has the highest energy and red has the least.

Then the facilitator may ask which is really more bent the red light or the violet light? Ask them also some superstitious beliefs that the students are familiar of related to the existence of rainbows. Then let them do Activity No. Then go back to the key questions to be able to summarize the concepts on visible light. The refractive index of prism varies with the wavelength or color of the light used.

This causes the different colors of light to be refracted differently. Then leave the prism at different angles, creating an effect similar to a rainbow Q4. Some colors visible in the prism were not observed in the water Q5.

Small value for refractive index is observed in red and large refractive index for red Q6. The refractive indices of the different color of light indicate that light of different colors travels at different speeds in the prism which accounts for the different amounts of bending.

The wavelength decreases from red to violet while the frequency increases from red to violet. White light separates into color light because it refracts with different refractive indices while passing through a medium like a prism. YES Q As the frequency of the color of light increase, the energy also increases. Red has the least frequency with the least energy and Violet has the highest frequency and the highest energy.

The higher the frequency of the color of light, the greater is its energy. The color spectrum wheel revisited Activity 5 Which color has the most energy? Conceptual physics 6th Ed. As in the previous grade, there will be three modules in this quarter: Module 1 is about Earthquakes and Faults.

In Module 1, we continue to emphasize the idea that our location on the globe is intertwined with what we experience in our daily lives. For instance, the Philippines is located along the Ring of Fire. This means that earthquakes and volcanic eruptions are normal occurrences in our country. We share the same fate with other countries that surround the Pacific Ocean, including Indonesia to the south and Japan to the north.

They too have faults in their land where energy is locked for some time before it is unleashed in devastating earthquakes. Similar to our two neighboring countries, we are surrounded by the sea. And whenever the seafloor is suddenly jolted by a strong earthquake, a tsunami is generated and our coastal areas are swamped with deadly waves. Mindanao and Mindoro have been victims in the not-so-distant past. In Module 2, we find out why we are prone to typhoons, too.

In fact, The Philippines is hit by about 20 tropical cyclones each year. This number is an average, so sometimes we get more than that. What conditions in the vicinity of our country favor the formation of tropical cyclones?

Our country is located near the equator, surrounded by bodies of water. This combination means there is heat to warm up the waters of the ocean and produce a lot of water vapor. The rising warm air will soon turn into a low- pressure area that may intensify into a tropical cyclone. If only the Philippines were at a higher latitude, it would suffer less tropical cyclones because the surrounding waters would be colder.

Or if the Philippines were at the equator, it would likely be free of tropical cyclones because there is no Coriolis force to make the air spin. Alas, there is no such luck. The Philippines is located right where tropical cyclones form and there is nothing to do but learn how to survive their annual onslaught.

In Module 3, we will take up comets, asteroids, and meteors. Luckily, the Philippines is not a favored target. But even without a direct hit, everyone will be affected if a really large chunk of rock came crashing from outer space. The last time that happened, it ended the reign of the dinosaurs. So studying these foreign objects may pay off in the long run.

The Ring of Fire refers to the region around the Pacific Ocean that are commonly hit by earthquakes and volcanic eruptions. Earthquakes will be covered in this grade level while volcanic eruptions will be tackled in the next. Every now and then, a strong earthquake hits the Philippines, leading to numerous deaths and widespread destruction. We cannot stop this natural event from occurring.

And up to now, scientists have not found a way to predict when an earthquake will occur. Thus, students must learn about earthquakes in order to survive. Key questions for this module What is a Fault? Earthquakes occur when rocks along a fault suddenly move.

The first thing to do then is to learn what a fault is. Let us go through the definition in more detail. We live on the surface of the crust. Why do earthquakes occur? What is the relationship between earthquakes and faults? All that is needed are sand and two pieces of cardboard and the students are ready to go. Tell the students to work on top of the newspaper to avoid sand spilling everywhere.

The activity is supposed to simulate what the ground looks like as rocks move along a fault.

Science 8 Teachers Guide | PDF | Series And Parallel Circuits | Force

Record it on the table. Each member will walk or run up the flight of stairs. Use a stopwatch or any watch to get the time it takes for each member to climb the stairs. Record the time in the 4th column. Solve for the energy expended by each member.

Record them in the 5th column of the table. Compute for the power output of each member. Who among the group members had the highest power output? What is the highest power output? Who among the group members had the lowest power output? What is the lowest power output? What can you say about the work done by each member of the group? Did each member perform the same amount of work in climbing the stairs? References and Links Henderson, Tom.

Work and energy. Conceptual physics. Saddle River, New Jersey. Kirkpatrick, L. Physics: A world view. Forth Worth: Saunders College. Ostdiek, V. Inquiry into physics. New York: West Publishing.

Science and Technology IV. SEDP Series. Philippines: Book Media Press, Inc. Although we do not see how this process actually takes place, its effects are evident. In fact, we rely on these effects everyday in many of the activities that we do. Understanding the concepts behind heat transfer therefore helps us do our activities more efficiently. You have learned in previous grades that heat transfer takes place between objects or places of different temperatures, and that heat transfers from an object of higher temperature to an object of lower temperature.

You have also learned that heat can be transferred through conduction, convection, or radiation, and that heat transfers either through moving particles or electromagnetic waves. Lastly, you also learned about some factors that affect heat transfer, like the conductivity of the materials.

This time, you will learn more about heat transfer by exploring its effects on materials. You will also learn about the factors that affect the amount of heat that an object can absorb or release and describe how these are related to the amount of heat transferred.

People often interchange the use of the terms heat and temperature in their daily conversation. They also think that heat and temperature are just the same. But for physicists, heat and temperature are two different concepts. So in this module, you will also learn the difference between heat and temperature. The energy that is actually contained in an object due to the motion of its particles is called thermal energy. The thermal energy of an object is changed if heat is transferred to or from it.

Since the amount of heat transferred relates to the amount of change in thermal energy, the term heat in this module is also used to refer to the measure of thermal energy transferred. Note also that the activities in this module involve hot and boiling water, so extra care should always be observed. Activity 1 Explaining hotness or coldness This first activity deals with one of the major effects of heat transfer, which is temperature change. You will describe the hotness or coldness of an object in terms of its temperature.

You will also compare the changes in the temperature of water to determine the relationship between the amount of heat transferred and the resulting temperature change. Materials Needed: 3 identical containers thermometer hot water tap water room temperature cold water What happens to solids, liquids, or gases when they absorb or release heat?

Does heat affect all kinds of materials in the same way? Are heat and temperature one and the same? Half-fill the three containers with equal amount of cold water. Arrange them next to one another as shown in Figure 1 below. Place your finger for a while into any of the containers. Try to recall your lesson on Heat Transfer in Grade 7 and answer the following questions: Q1.

What actually transferred when you dipped your finger into the water? In what direction did it transfer? Discuss your answers with the group. Try to estimate the temperature of the water in the containers. Measure with a thermometer the temperature of the water in each container. Record your measurements in Table 1 below. Note: The initial temperature of the water in each container should be the same as they come from the same source.

Figure 1 1 2 3 How close is your estimated value to the measured temperature of the water? Add the same amount of hot water to container 1, tap water to container 2 and the same cold water to container 3. Leave the containers for a while. Dip your fingers again, this time into the three containers. Make sure that you do not dip the same finger into the containers.

What do you think causes the difference in the hotness or coldness of the water inside the containers? Measure and record the temperature of the water in all containers. Calculate the change in the temperature of water in each container.

In which container s is heat transfer taking place? What evidence best supports your answer? Within this container, which absorbs heat?

Which gives off heat? In which container was there the greatest amount of heat transferred? What is the basis of your answer? How are the amount of heat transferred and the change in temperature of water related? If the object absorbs heat its temperature rises.

How do we explain the rise in temperature when heat is absorbed? In this next activity, you will take a closer look at what is actually happening at the particle level and infer what happens to the particles of an object when heat is added to it. Materials Needed: 3 transparent containers 1 thermometer 3 plastic droppers hot water tap water room temperature cold water dye Food color Procedure: 1. Fill the three containers separately with cold water, tap water, and hot water.

Measure the temperature of the water in each container. Record your measurements in Table 2 below. With the dropper, place a drop of dye into the center of each container as shown in Figure 2.

Note: It is better if you place drops of dye into the three samples simultaneously. Carefully observe and compare the behavior of the dye in the three containers. Write down your observations in Table 2. What similarities and differences did you observe when a drop of dye was added to each container? In which container did the dye scatter the fastest? In which di it scatter the slowest?

How do you relate the temperature of the water to the rate of scattering of the dye? All the objects that you see around you that are moving possess kinetic energy. But do you know that even the very small things that you cannot see, like the particles of objects, are also moving and have kinetic energy? Take for example the water inside the containers in Activity 2. The scattering of the dye through the water indicates that the particles of water are moving.

You will learn more about the movement of the particles of matter in the third quarter when you discuss about the Particle Theory of Matter. You also noticed that the rate of scattering of the dye throughout the water differs in each container. It can then be inferred that the speed of the particles of water varies in each container.

Since kinetic energy depends on speed, the kinetic energies of the particles also vary. In which container are the particles of water moving fastest? In which container are the particles moving slowest? How is temperature related to the speed of the particles? Figure 2 How is temperature related to the kinetic energy of particles? If heat is added to an object, the particles of the object gain kinetic energy and they move faster.

Since temperature is directly related to kinetic energy, any gain in kinetic energy would cause the temperature to increase. Thermal Expansion, the Working Principle of the Mercury Thermometer You know that temperature is measured by the use of thermometer. You have most probably used this device many times.

The thermometer commonly available in our schools is the liquid thermometer, which has a column of either mercury or alcohol. When the thermometer is placed in contact with any object the mercury column either rises or drops.

Now, why does the liquid inside the tube of the thermometer go up or down? This happens because the mercury inside the tube expands or contracts in response to a change in temperature. When the thermometer bulb is placed in hot water, the liquid inside the tube expands. As it does, it takes more space and so it goes up the tube.

When the bulb is placed in cold water, the liquid contracts and so it goes down the tube. In physics, this is called thermal expansion, another effect of heat transfer.

But thermal expansion does not apply only to the liquid inside the thermometer. In fact, it applies to almost everything around us, be it a solid, a liquid, or a gas. If allowed by your teacher, you may try this simple activity to demonstrate expansion of a solid when heated.

Thermometers in a hot and b cold liquid You will need: copper wire around 2m long , candles, meterstick, 2 iron stands with clamps or rings, standard weight or any mass around g What to do: Prepare the setup as shown below. Make sure that the ends of the copper wire are tied or clamped firmly. Hang the weight in the middle of the wire. Use the candles to warm the wire at different points.

Do this for 1 or 2 minutes and observe what will happen to the height of the weight. If you tried out this experiment, you would have observed that when you heated the entire length of the wire, the weight moved down or its height decreased a little. This indicates that the wire expanded or increased in length when heated. There are so many applications of thermal expansion around us. Some are beneficial to us; others can also be a burden to us.

One example of thermal expansion in solid is the sagging of electrical power lines or telephone wires on hot days. This happens because heat causes them to expand. Have you ever wondered why it is difficult to open a jar that was just taken out of the refrigerator or why motorists are advised not to overinflate their car tires or fill their gasoline tanks to the brim?

How will you apply the concepts of thermal expansion to explain all these? WeightCopper wire Ruler or meterstick Figure 4. Setup for expansion of wire experiment For example, you know that water can change from solid ice to liquid water or from liquid to gas steam. The next activity will allow you to observe the changes that take place when ice turns to liquid water.

Activity 3. After this activity, you should be able to answer this question: What happens to the temperature of water while changing from ice to liquid water? Materials needed: crushed ice 1 glass container timer stopwatch stirring rod Procedure: 1. Put some crushed ice and a little cold water into the container. Stir the contents of the container for few seconds; then, measure the temperature of the contents. Avoid letting the thermometer touch the bottom of the container to ensure that you are actually measuring the temperature of the water.

Table 3: Temperature readings for melting ice 3. Repeat step 2 every 2 minutes. Make sure that you stir and measure exactly the same way each time. Record each measurement in Table 3. Why does the ice inside the container melt after sometime? Continue measuring until the ice has totally melted and even after it has already melted completely around minutes more. Construct a temperature against time graph. Draw a smooth line that passes through almost all the points.

Which is your dependent variable? Which is your independent variable? Note that the independent quantity is plotted along the X-axis while the dependent quantity is plotted along the Y-axis. Describe your graph. Describe the temperature of the water while the ice melting. Describe the temperature of the water after the ice has melted. Were you able to see in your graph a horizontal line similar to the part encircled in Figure 5? This was during the time when solid ice was turning to liquid water.

During this stage, the temperature of the water remained the same, as shown by the horizontal line. Remember that a change in temperature indicates a change in kinetic energy. In this case, there was no change in the kinetic energy of the particles. So what happened to the heat energy that was continuously transferred to the water?

The temperature of the water will only start to increase after the ice has totally melted. What if you continue to heat the water further until it boils? What do you think will happen to the temperature of the water? Fill the beaker with mL hot water and place it above the alcohol burner using the tripod with wire gauze. Measure and record the temperature of the water every 2 minutes until it boils. Once the water starts to boil, continue taking the temperature for more minutes.

Plot the graph of temperature against time. Describe and interpret your graph. What similarities and differences have you noticed between your graphs in Activity 3. If you heat up the same sample from ice to water then from water to gas vapor and plot the graph of temperature vs time, it would look like the graph in Figure 5.

The graph shows that the ice absorbs heat as evidenced by the temperature rise; the temperature remains the same when ice starts to melt and until all the ice has melted; then the temperature rises again until water boils. The temperature remains constant at boiling temperature when water starts turning to steam and until all the liquid water has become water vapor.

This is shown by a greater increase in temperature of the object that absorbed the heat. What other factors determine the amount of heat that a body can transfer? Activity 4 What is the relationship between the mass of a material and the amount of heat it can transfer? Task: In this activity, your group is assigned to plan and conduct a simple investigation to determine the relationship between the mass of a material and the amount of heat that it can transfer.

You need to gather and analyze data to come up with answers to the question given above. Apply what you learned in grade 7 about doing simple investigations. Below are some guides to help you with your task. What are your variables?

Independent variable: Dependent variable: Controlled variable constant : b. What materials are you going to use for your simple investigation? What quantities are you going to measure for your data? How are you going to analyze and present your quantities data to describe the relationship among the variables?

Write your step-by-step procedure. Let your teacher check your procedure first before you proceed. Precautions should always be observed. Present your data systematically. If you were successful in your investigation, you would have realized that the amount of heat transferred depends not only on the temperature of the material.

It also depends on the mass or amount of material. Objects with greater mass have more thermal energy and can transfer more heat. This time, you will study another thermal property of materials —their ability to absorb or release heat that results in temperature change.

In science, the amount of heat needed by a material to increase its temperature by a degree is called heat capacity C. To be more specific, the term specific heat capacity c is used, and this refers to the amount of heat required to increase the temperature of one unit mass of a given material by one Celsius degree. Materials: 2 identical small containers each with mL of liquid sample 2 identical large containers large enough to accommodate the small containers 2 thermometers hot water liquid samples: water, cooking oil Note: Store the liquid samples in the same room to ensure that both are at room temperature when you do the activity.

Procedure: 1. Pour mL of water into one of the small containers and the same amount of cooking oil into the other container. Measure and record their initial temperature in Table 4 below. Place the small container with oil in a larger container with hot water. Make sure that the hot water does not mix with the liquid sample. Record your measured heating time in Table 4. Do the same with the water sample. Make sure that the amount and temperature of the hot water is the same for both samples.

Record also your measurement in Table 4. Which liquid requires more time to increase in temperature by 5 degrees? Which liquid requires more heat to increase in temperature by 5 degrees? Which liquid has a greater heat capacity? Different materials have different specific heat capacities. Many metals have low specific heat capacities. This makes them easy to heat up and cool down.

Water, on the other hand, has a high specific heat capacity and so it takes a long time to heat and a long time to cool. This makes the water a good coolant for car radiators. Because of its high specific heat capacity, it can absorb a large amount of heat without causing its temperature to rise too high. Heat and Temperature So far, you have already recognized the relationship between heat and temperature. So how do they differ? Go back to your previous experiments and analyze your findings.

Then try to answer questions below. Which can transfer more heat, 1 cup of boiling water or 1 teapot of boiling water? Explain your answer. If you increase the amount of the boiling water and tap water twice, will their temperature change? You may try this out if you have time. So how are heat and temperature different?

Well, here are the important points to consider about the difference between heat and temperature. First, heat is a form of energy while temperature is not a form of energy. Temperature is a measure of the average kinetic energy of the particles and it does not depend on the mass of the object.

It can be measured directly with the use of thermometers. Heat cannot be measured directly. But you can make use of the measurable quantities related to heat to determine how much heat Q is absorbed by the object.

Heat and temperature. Sci Ed, Many of the activities we do everyday depend on electricity. Can you watch your favorite show on TV without electricity? Can you use your computers without electricity? Imagine our life today without electricity. You have been learning a lot about electricity from Grade 3 to Grade 7. You have learned about its sources and uses; what materials make good conductors of electricity; what makes up an electric circuit; and how electrical energy is transferred or transformed into other forms of energy.

In this module, you will learn more about electricity. There are three quantities that you should be familiar with in the study of electricity. These are electric current, voltage, and resistance. You will use the relationships among these quantities in learning about circuit connections. You will also learn that some of the safety precautions you have been warned about can be explained by the relationships among voltage, current, and resistance.

At the end of this module you should be able to answer the following questions: How do voltage and resistance affect electric current?

What are the safety precautions needed in using electricity? You also learned that a complete or a closed circuit provides a path for electrical charges to flow. Electric current is a measure of the number of electrical charges passing through a cross- section of a conductor in a given time.

The direction of conventional current or simply current is from the positive terminal of the battery to the negative terminal. The symbol for current is capital letter I. The unit, ampere A , is named after Andre-Marie Ampere, a French physicist who made important contributions to the theory of electricity and magnetism.

An ammeter measures electric current. Figure 1 shows how the ammeter is connected in a circuit. The positive terminal of an ammeter is connected to the positive terminal of the energy source e. Ammeter connected in a circuit Voltage What makes the charges move in a closed circuit? In Module 2, you learned that when work is done on an object, energy is transferred which can become energy of motion of the object.

In a circuit, work must be done on the charges to make them move. The battery supplies the energy in electric circuits. The chemical energy in the battery is transformed to electrical energy. This electrical energy moves the charges in a circuit. A battery consists of several dry cells or wet cells. Both dry and wet cells contain a conducting medium called electrolyte. The batteries we use in flashlights and watches are dry cells. The unit, volts V , is named after the Italian physicist Alessandro Volta who invented the voltaic pile, the forerunner of what we now call the dry cell.

A voltmeter measures voltage. Figure 2 shows how the voltmeter is connected in a circuit. The voltmeter should be connected across the load being tested. The positive terminal of a voltmeter is connected to the positive terminal of the bulb while the negative terminal is connected to the negative terminal of the bulb as shown in Figure 2. Voltmeter connected across the load If voltage is needed for charges to flow, how does the amount of voltage affect current?

Find out in Activity 1. Activity 1 Current and voltage Objectives: After performing this activity, you should be able to: 1. Construct a simple circuit using a dry cell, a bulb, a switch and an ammeter. Close the circuit by turning on the switch. Observe the bulb and the ammeter. Record the ammeter reading in Table 1. Upon completion of the task, switch off the circuit. Ammeter connected in a circuit with one dry cell Q1.

What is the reading on the ammeter? Add another dry cell to the circuit. Record the electric current measurement in Table 1. Once the task is done, turn off the switch. Ammeter connected in a circuit with two dry cells switch battery bulb ammeter Compare the brightness of the bulb with one dry cell to its brightness when there are two dry cells in the circuit. What is the ammeter reading this time? What can be inferred about the current passing through the bulb?

Connect the voltmeter in the circuit as shown in Figure 5. Switch on and record the voltage in Table 1. Voltmeter connected in a circuit with one dry cell Q5. What is the voltmeter reading? Record the voltmeter reading in Table 1. Observe the brightness of the bulb. Voltmeter connected in a circuit with two dry cells Describe the brightness of the bulb. What is the voltmeter reading this time? What can be inferred about the voltage across the bulb? Refer to Table 1, how are voltage and current related?

In Activity 1, the current and voltage in circuits with 1 dry cell and 2 dry cells were compared. You observed that the ammeter and voltmeter readings are greater in the circuit with 2 dry cells as compared to the circuit which has only one dry cell. Also, the bulb in the circuit with 2 dry cells glowed brighter than the bulb in the circuit with only 1 dry cell. The activity showed that as the voltage increases, the current also increases.

However, a circuit is not only about voltage and current. There is another component which is the load. A load is any component in a circuit that converts electricity into light, heat, or mechanical motion.

In the circuit you constructed in Activity 1, the bulb is the load. If two bulbs were used in the circuit, would there be a change in the circuit current? You will find out in Activity 2. Resistance When electric charges flow through the wires and loads of the circuits they encounter resistance or a hindrance to their movement. So another factor that affects the flow of charges or current is resistance.

The symbol for resistance is capital letter R. How is current affected by the resistance of the load in a circuit? Do activity 2 to find out. Activity 2 Current and resistance Objectives: After performing this activity, you should be able to determine the relationship between electric current and resistance.

Construct a simple circuit using one bulb, 2 dry cells and an ammeter as shown in Figure 7. Record the electric current measurement in Table 2. Ammeter connected in a circuit with one bulb and two dry cells 2. To increase the resistance, add another bulb in the circuit. Connect the ammeter and record the electric current measurement in Table 2. Ammeter connected in a circuit with two bulbs and two dry cells To further increase the resistance, add another bulb in the circuit.

An ammeter connected in a circuit with three bulbs and two dry cells Table 2 Q Based on Table 2, what happens to the current in the circuit as the resistance increases increasing of bulbs?

Connect the ammeter at different points around the circuit shown in Figure Make sure that the positive terminal of the ammeter is connected to the positive terminal of the dry cell while the negative terminal is connected to the negative terminal of the dry cell. Ammeter connected between two bulbs in a circuit No. Compare the current at different points in the circuit.

What can you infer about the current through the circuit? In Activity 2, you added bulbs to the circuit to see if the current in the circuit will be affected. You observed that keeping the number of dry cells the same, adding more bulbs resulted in a decrease in current. Since adding more bulbs means increasing the resistance in the circuit, it can be inferred that the resistance limits the current in the circuit.

You further observed that the current is the same in any part of the circuit as evidenced by the ammeter readings. How is the result in Activity 1, related to the result in Activity 2?

The results of Activity 1 showed that for a fixed resistance one bulb , as the voltage increases, the current also increases. For Activity 2, the results showed that keeping the voltage the same 2 dry cells , when the resistance increases, the current decreases.

At this point, you are already very familiar in constructing a circuit. Grade 8 Unit B: Cells and Systems Students learn to interpret life at a variety of levels, from individual cells to complex organisms. Cells AND Study and teaching. Circulation AND Study and teaching. Digestion AND Study and teaching.

Health AND Environment. Organs AND Study and teaching. Grade 8 Unit C: Light and Optical Systems In learning about light, students investigate its interactions with different materials and interpret its behaviour using a geometric ray model. Light AND Optics. Optics AND Activity programs. Grade 8 Unit D: Mechanical Systems Machines are used for many purposes in our daily lives when we need to transfer energy into motion or move materials in a controlled way.

Friction AND Study and teaching. Hydraulics AND Pneumatics. Hydraulics AND Study and teaching. This shows that in this type of connection, voltage is the same across any two points in the circuit. Answers to Questions: Q There is only one path for current in Circuit A.

The brightness of the bulbs in Circuit B remains the same as bulbs are added in the circuit. The current in Circuit B is bigger than in Circuit A. Safety in Using Electricity Fires can happen when the wires start heating up causing combustible parts of the house to be set on fire.

The wires heat up when the current passing is more than what the wires can carry. In this case there is an overloading of the circuit. An example of how the circuit gets overloaded is by plugging a lot of appliances in a common outlet like an extension cord. Another instance of overloading of the circuit is the presence of short circuits. Short circuits happen when wires with defective rubber insulation touch each other so the current does not pass to the supposed path it should take.

In the wires the electrons that flow in a closed circuit collide with the atoms of the conducting wire. As the collisions take place the kinetic energy of the metal atoms increases. The increased kinetic energy of the atoms is dissipated as heat. You learn in the module on heat that temperature is related to the kinetic energy of the moving particles. The higher the kinetic energy of the particles, the higher will be its temperature. The higher the current passing through the wire, the more collisions between the electrons and the atoms of the wire take place.

In the end the wire will become hot. So just imagine how much heat will be generated from an overloaded circuit. The first part shows how increasing the current can cause the wires to heat up.

The second task shows how a short circuit happens. The hotter the wire the deeper will be the cut made on the candle. Stay safe! Activity 4 The candle touching the wire melts. The current in the circuit increases. Heat is produced along the wire. The bigger the current in the circuit, the wire becomes hotter, and the more the candle will melt. The light goes off when the wires touch each other. The current took the path of the exposed part of the wire touching each other.

The resistance encountered in the short circuit where the charges flowed is lower. The current in the short circuit increases. Short circuits cause fire when the nearby materials near the wires becomes so hot and starts to burn. Resistance decreases as more appliances are connected to one outlet. The total current increases.

Overloading the circuit can make the wires hot setting combustible materials on fire. References and Links Henderson, Tom. In the course of discussion, wave characteristics and properties particularly reflection and refraction will be taken into account. From the activities, students will be able to identify also the factors that affect the speed of sound.

At the end of the unit, students should be able to: 1. Sounds can be produced without using any material objects. Hitting an object harder changes the pitch of the sound produced. Sounds can travel through empty space a vacuum. Sounds cannot travel through liquids and solids. Sound travels slower in less dense medium. The greater the density of the medium the faster the sound is transmitted.

Related Misconceptions Solid, Liquid, or Gas? How does the temperature of the medium affect the speed of sound? How are reflection and refraction manifested in sound? Students may be asked to sing some of the popular tunes and ask them who are fun of watching concerts? Also ask them why concerts are usually done during night time and not during day time. Probe further until the concept of sound as a wave is deduced. In this activity the students will use a metal slinky to 1 distinguish the different characteristics of waves; 2 determine the frequency and wavelength; and 3 compute the wave speed based on the frequency and wavelength.

In hotter medium or cooler medium? Introduce Activity No. In Hotter or Cooler? In this activity the students will be able to determine how temperature affects the speed of sound. Let them do Worksheet No. Then introduce Activity No. The salt bounced up and down.

The amplitude of the wave. The other colored beads collided with the blue bead. Yes Q Sound wave is classified as a longitudinal wave.

In this activity, students will be able to distinguish the different characteristics of waves; determine the frequency and wavelength; and compute the wave speed based on the frequency and wavelength Characteristics of waves: Comparing longitudinal and transverse waves Activity 2 The dancing salt and the moving beads!

Wavelength is decreased provided the frequency of shaking or disturbing the medium is the same or constant. In this activity, students will be able to distinguish which material transmits sound the best. The sound seems louder in the string as compared to air. Yes In this activity, students will be able to infer using improvised chimes that closely spaced particles of the medium are best transmitters of sound.

Chime 2 Q Chime 2 Chimes Activity 4 Sound race Where does sound travel fastest? Chime 3 Q The chime with packed string objects produces sound that reached the farthest distance. The more closely distanced the stringed objects in the chime, the better the sound is transmitted. In this activity, students will be able to be able to determine how temperature affects the speed of sound.

HOT cylinder Q The higher the temperature, the faster the sound travels. In this activity, students will be able to be able to observe how longitudinal waves reflect and refract. Reflecting and refracting sound Activity 6 Faster sound In hotter or cooler? Activity 5 The compressions or rarefactions bounce off after hitting the wall Q No they are not found on the same positions Q Sound will also bounce off when it strikes a fixed end or the wall Q The frequency of the wave increases Q Increase in frequency of the sound is manifested as change in pitch Q Amplitude increases Q Louder sound is observed Q Among the characteristics and properties of light, we focus on refraction and specifically dispersion of light.

We will try to find out through simple activities on how light disperse to form the colors of light. We will also try to find the hierarchy of colors of light in terms of frequency, wavelength, and energy. The different activities provided in this module will make us realize the beauty of everything with light.

Key questions for this module How are refraction and dispersion demonstrated in light? In the different colors of light, which is bent the most and the least? Why do we see spectacular events in the sky like rainbows, red sunset and blue sky? The Colors of Light.. The students will be able to infer that white light is made up of many different colors of light and each of these colors of light bends differently.

Students should be able to come up with a presentation of the scientific explanations of certain superstitious beliefs related to observable phenomena in the sky. Ask students whether they are familiar with the character. Ask them also if there is a connection between the character and the lessons. Ask the students if they could guess some information or concept from the name of the character.

If the students recognize the colors of light then ask key question no. Follow it up by the 1st 2 key questions. Have a recall of the equation for index of refraction and let them do Activity No. Let them perform Activity no. This activity is composed of two parts. One makes use of locally available materials while the other makes use of the standard materials like prism and artificial source of light.

A comparison of the two may be highlighted during the discussion of results. This will be explicitly described by the students during the processing when they present their outputs which would include the relation of the bending and the index of refraction of the color of light.

From the given materials, students will be able to determine the relationship between frequency and the energy of the colors of light. Then the facilitator may ask which is really more bent the red light or the violet light? Ask them also some superstitious beliefs that the students are familiar of related to the existence of rainbows. Then let them do Activity No. Then go back to the key questions to be able to summarize the concepts on visible light.

The refractive index of prism varies with the wavelength or color of the light used. This causes the different colors of light to be refracted differently.

Then leave the prism at different angles, creating an effect similar to a rainbow Q4. Some colors visible in the prism were not observed in the water Q5.

Thus, blue light with greater refractive index refracts more and appears at the bottom of the red light Q7. Yes Q8. The greater the refractive index of the color of light, a greater bending is also observed. Red vs Violet Activity 3 The colors of the rainbow Activity 2 RED Q Violet Q The wavelengths and frequencies of the colors of light vary. The wavelength decreases from red to violet while the frequency increases from red to violet. White light separates into color light because it refracts with different refractive indices while passing through a medium like a prism.

YES Q As the frequency of the color of light increase, the energy also increases. Red has the least frequency with the least energy and Violet has the highest frequency and the highest energy. The higher the frequency of the color of light, the greater is its energy. The color spectrum wheel revisited Activity 5 Which color has the most energy?

Mindanao and Mindoro have been victims in the not-so-distant past. In Module 2, we find out why we are prone to typhoons, too.

If only the Philippines were at a higher latitude, it would suffer less tropical cyclones because the surrounding waters would be colder. Or if the Philippines were at the equator, it would likely be free of tropical cyclones because there is no Coriolis force to make the air spin. Alas, there is no such luck. The Philippines is located right where tropical cyclones form and there is nothing to do but learn how to survive their annual onslaught.

Earthquakes will be covered in this grade level while volcanic eruptions will be tackled in the next. Every now and then, a strong earthquake hits the Philippines, leading to numerous deaths and widespread destruction.

Key questions for this module What is a Fault? Earthquakes occur when rocks along a fault suddenly move. The first thing to do then is to learn what a fault is. Let us go through the definition in more detail. We live on the surface of the crust. Why do earthquakes occur? What is the relationship between earthquakes and faults?

All that is needed are sand and two pieces of cardboard and the students are ready to go. Tell the students to work on top of the newspaper to avoid sand spilling everywhere.

The activity is supposed to simulate what the ground looks like as rocks move along a fault. Figure 1A is the starting point. Lay the two sheets side to side. Make the sand top flat so everything can be seen clearly.

The two parallel lines are there so that the displacement will be obvious to the observer. Figure 1B, C, and D shows how a crack forms in the sand. A fault-y setup Activity 1 Figure 1A-D. Sheets are moved in the direction shown by the arrows. A crack forms in the sand and the lines are displaced. Before doing this activity, experiment with sand of different sizes. If the sand size is too big, the expected crack in the sand may not form or may be hard to see. Look at Figure 1B, C and D. See the crack that goes from left to right?

The students are supposed to see that. After the activity, direct the students to Figure 4 in the student module. This is Figure 2 in this guide. Ask the students to compare what they saw in the activity to what is shown in the picture. The students are supposed to see that the crack in the sand is similar to the break across the road in the picture. You can then tell them that that is how a fault may look out in the field.

Answers to questions Q1. As you move the sheets, what is formed in the sand? What happens to the lines? Answer: The lines are shifted or displaced. Left The short box cover is put within the long box cover. Right Sand is poured into the nested covers. You can also demonstrate movement in the vertical direction. The ground will be observed to move up or down. All that is needed is sand and a narrow box cover. Get the box cover and cut it so that the length of one piece is twice the other Figure 3.

If you cannot find a box cover, make one using cardboard. Place the shorter box cover within the longer one Figure 4, left photo. Put sand in the nested box covers. Shake the box side to side so the surface of the sand will become level Figure 4, right photo. Now, slowly pull the sides of the box covers as shown in Figure 5. Ask the students to observe carefully. Figure 3.

Sand and a narrow box cover cut into two pieces The box covers are pulled outward. Figure 7. The box covers are pushed toward each other. Figure 6.

Left As the box covers are pulled outward, cracks form in the sand. Right With more outward pulling, the sand subsides. As you can see in Figure 6, two parallel cracks form in the sand. If you continue to pull, the sand in the middle of the cracks will subside move down , forming a depression.

This simulates what happens when the ground is pulled apart by forces within the Earth. Faults form, a portion of the land sinks, and a valley is formed. Now, re-assemble the box covers as before. Do not forget to make the surface of the sand flat. This time, push the sides of the box covers toward each other Figure 7. Let the students observe what happens. Left A tiny hump is formed in the sand. Right The hump as seen from another angle.

As can be seen from Figure 8, the opposite happens. Instead of the sand sinking, the sand forms a tiny ridge. Unfortunately, this model does not show a crack in the sand that would represent a fault. In the real world, a fault is formed when the ground is squeezed by forces from inside the Earth. A portion of the land is pushed up, and mountains are formed. Note: Use fine sand when performing this demonstration.

Coarse sand does not work as well. Experiment using different materials. How do faults produce quakes? Now that students have an idea of how faults look, let us show them how earthquakes occur along faults.

To answer this question, the students will perform two short activities. In this activity, two small boxes are needed. The cartons that fruit juice drinks are packaged in are perfect. Setting it up is simple Figure 9, left photo. The activity can be performed in groups, or as a class demo if you are pressed for time. The activity is supposed to show the sudden jerk that occurs when rocks move along a fault in an earthquake. Left Setup before simulated earthquake Right After simulated earthquake.

The students may find it tricky to attach the rubber band to the box. Just punch two holes in the box, close enough so you can loop a paper clip or a thin wire through them. Then attach the rubber band to the clip. Look at the photos in Figure 9 so you know how it should be done. The student is supposed to pull on the rubber band attached to one box while holding the other box in place.

The rubber band should be pulled forward and horizontally, not sidewise, upward or downward. Expected result: The box will not move at first because it is taped to the other box which is being held. The rubber band will stretch. The tape will suddenly come off. The box attached to the rubber band will jerk forward and the house will topple over Figure 9, right photo. This simulates the sudden movement that occurs along a fault.

The success of this activity depends on the tape, which represents friction in real life. If it is too sticky, the tape will never come off, no matter how much the rubber band is pulled. Tape it on just enough for the rubber to stretch a bit before the box jerks free from the tape. In real world terms, this is what happens. Energy from inside the Earth exert a force on the rocks along faults. But the rocks do not move right away because of friction. The roughness of the rocks keeps them from slipping past each other.

But when the limit is reached, the rocks suddenly slip—earthquake! What happens to the rubber band? Answer: The rubber band stretches. What happens to the box attached to the rubber band?

Answer: The box jerks forward. While Activity 2 simulates the sudden movement along a fault, it does not show the shaking that accompanies the sudden movement. Activity 3 will demonstrate this. This activity needs the simplest of materials: just two plastic rulers and some clay.

The activity is supposed to demonstrate the shaking that occurs when the rocks along a fault suddenly jerk free from being locked in place. Even if this activity is simple, it should be tried out first before doing it in class. What is expected to happen? The rulers are held together at the ends by a bit of clay Figure The rulers are then bent into an S-shape.

When the bending goes beyond a certain limit, the rulers separate, vibrating in the process. The right ruler is pushed away while the left one is pulled back until the rulers are bent into an S.

Choose rulers that vibrate nicely. If the plastic rulers are stiff, they will not vibrate. If the rulers are too soft, they will bend without separating. It is best if the rulers are of the same kind and length. The rulers must be held tightly. If they are held loosely, the rulers will not vibrate.

Experiment to find out the right amount of clay and how much the rulers should be pressed together. If you use too much clay, it will take a long time before the rulers separate. But if you use too little, they will separate before there is any bending, and vibration will be less.

It is challenging for students to transfer what they learned in an activity to real life. You could use the following drawings Figure 11 to make this activity more concrete. Let the students imagine the rulers to be rocks making up the ground. Drawing A shows the land before fault movement.

In B, the rocks have undergone some bending. In C, friction has been overcome and the rocks have snapped straight from their bent position. It is this motion that is demonstrated by the vibrating rulers. When bending is too much, the rulers snap straight and vibrate. Figure A, before fault movement. B, rocks bend, storing energy. C, friction is overcome, rocks snap straight, releasing energy in the form of earthquakes. Answers to Questions Q8. What happens when bending becomes too much?

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