Project ASK Electric Circuits

Transcription

1 Project ASK Electric Circuits Draft/Field Test Version January 2008

2 ELECTRIC CIRCUITS SESSION 1: Sparks, Shocks, and Static Electricity BIG IDEAS To get ready for the unit on electricity, participants first share what they already know about common uses of electricity and how it influences our everyday lives. Then they discuss electrical safety and generate a list of rules. Note: The equipment provided in this unit does not cause injury when used correctly. Finally participants do experiments with static electricity, ask their own questions, and do further experiments to try to find answers. MATERIALS For each participant 1 science notebook For each group 1 balloon pieces of Styrofoam small scraps of paper a sink with running water For demonstration 1 D-cell battery 1 wire 1 bulb PREPARATION 1. Provide a science notebook or paper for each participant. 2. Collect the rest of the materials listed above. 3. Locate a sink with running water for the activity in Part 2. Project ASK Electric Circuits / 1

3 ACTIVITIES PART 1: What do we know about electricity? PURPOSE: for participants to share what they already know about electricity. A. Hold a brainstorming session on the properties and the everyday uses of electricity. 1. Open a discussion about electricity. Use some of these questions: Imagine we had no electricity. How would our day have been different today? Look around you. What would be missing if there were no electricity in the building? Do you own any objects powered by electricity? What are they? How are they powered (battery or outlet)? Have you ever experienced naturally occurring electricity? For example, have you seen or felt sparks? Have you seen an electrical storm with lightning flashes? Describe what you experienced. 2. Invite other comments. Ask: What else do you know about electricity? How does it work? Let participants know that they will be learning more about how electricity works in the coming weeks. B. How can we keep safe when working with electricity? 1. Ask students to help you create a list of safety rules. You may want to write the rules down as students mention them. Here is a sample list: SAFETY RULES FOR ELECTRICITY Don t stick anything into a wall outlet except a plug. Don t touch an open socket. Keep appliances (like hair dryers and radios) away from water. If you see a fallen power line, don t touch it. Call Then expand on the conversation to talk about safely using the equipment that participants will be working with first: batteries, wires, and bulbs. Show participants the equipment and make the following points: We use many different kinds and sizes of batteries as sources of electric power. Batteries used in this unit can give a mild shock but only if you connect more than 24 or so in a series. We will not do this. Project ASK Electric Circuits / 2

4 The wire is made of copper covered with a layer of plastic. The copper part may get warm. Never stick the wire in an outlet. The bulbs are very small, but can still generate heat. The glass dome can also break. Treat the bulbs gently and carefully. We will not use rechargeable batteries because they can cause burns when short-circuited. We ll learn more about short circuits in another session. PART 2: What can static electricity do? PURPOSE: to experiment with static electricity. A. Talk about common experiences with static electricity. 1. Explain that there is another kind of electricity in addition to the kinds we get from batteries or through outlets. We call it static electricity. Then ask: Have you ever scuffed your feet along a rug then touched a metal doorknob? What happened? Have you ever taken off your hat in winter and had your hair crackle or stand up? These are examples of static electricity. Can you think of others? B. Do some experiments to find out more about static electricity. 1. Distribute the balloons and have participants blow them up and tie them tightly. Challenge them to stick the balloon to the wall, using nothing but the balloon and the wall. Then ask: How can we make electricity work for us? What can you do to the balloon to generate static electricity? (Participants may suggest rubbing it on some fabric or against their hair.) Let them experiment with generating static electricity in the balloon, then ask them to find out if they can stick their balloons onto the wall now that the balloon is charged. Project ASK Electric Circuits / 3

5 2. Distribute the bits of paper and Styrofoam and have participants observe the effect the balloon has on them. At the same time, send small groups to the sink. Have them run a thin stream of water and maneuver the balloon into different positions to observe how the water behaves. Static electricity in action. 3. Encourage participants to ask questions and to try to find their own answers by doing more experiments. 4. In their science notebooks, have students record what they observed and what they think was happening. JOURNAL PROMPT How did you make the balloon stick to the wall? What happened when you placed the balloon near the bits of paper? Near the Styrofoam? How did the water act when you brought the balloon close to the stream? What questions did you have? What other experiments did you do to try to answer your questions? 5. Discuss the results of the experiments. Ask participants what they observed and why they thought those things happened. They will have seen that when the balloon was charged with static electricity, it was attracted to and stuck to the wall; it attracted and repelled bits of paper and Styrofoam; and it bent a stream of water. Rubbing the balloon transferred electric charge between the balloon and the fabric with which it was rubbed. Objects with different electric charges cause invisible electric fields that can be observed by their effect on visible objects. TIPS ON PREPARING FOR THE NEXT SESSION Please look at the Preparation section of Session 2 for information on how to cut and strip wires and organize the materials that each participant will need. Set aside about 20 minutes to get the materials ready. Project ASK Electric Circuits / 4

6 ELECTRIC CIRCUITS SESSION 2: Lighting Bulbs and Turning Motors BIG IDEAS Participants begin by constructing simple circuits in which they light a bulb and make a motor turn. They use their hands to connect all the parts of the circuit, and this helps them to figure out exactly which parts need to be in contact. MATERIALS For each participant 1 science notebook 1 storage container such as a large zip-lock bag or a shoebox 1 D-cell battery 1 bulb 1 6-inch piece of wire (15 cm) 1 motor For the teacher 1 wire stripper PREPARATION 1. To prepare the wire: Cut two 6-inch (15 cm) pieces of wire for each participant. Use the wire stripper to remove about 3/4 of an inch (2 cm) of plastic insulation from each end of the wire. Use wire strippers to remove the plastic insulation from each end of the wire. Project ASK Electric Circuits / 5

7 2. For Part 1, set out 1 battery, 1 bulb, and 1 piece of wire for each participant. Provide a storage container for each person. 3. For Part 2, add a motor to the supply table. TIP: HOW TO MANAGE ALL THOSE PARTS Much of the excitement of this unit comes directly from the real equipment that participants get to use. But managing all those pieces can be a chore. Here are some suggestions: Set up a distribution center for equipment so participants can get their own supplies, cafeteria style. Emphasize that participants are responsible for picking up their own equipment and then storing it neatly afterwards. Provide each person with a storage container. For example, shoe boxes or large gallon-sized zip lock bags work well. Have students put their names on the containers. Project ASK Electric Circuits / 6

8 ACTIVITIES PART 1: How many different ways can you light the bulb? PURPOSE: for participants to discover several different ways of building a circuit using only one battery, one wire, and one bulb. Peer Coaching Participants who have had experience with the Electric Circuits unit will no doubt remember something of how to build many different kinds of circuits. It is important to let those with no experience discover how to light the light and run the motor on their own initially. Then, when it is time to experiment with more complex circuits, those with experience can be teamed up with the novices who will benefit from their peer teaching. A. Challenge participants to light the bulb several different ways. 1. Have participants pick up one wire, one battery, and one bulb from the distribution center. Ask them to find several different ways to light the bulb. 2. In their notebooks, ask students to record the different ways they found to light the bulb. JOURNAL PROMPT Draw a picture to show each of the different ways you made the light bulb light. B. Discuss the findings. 1. Give participants the opportunity to demonstrate the different ways they lit the bulb. For your information, here are four possibilities: Four possible ways to light the bulb Project ASK Electric Circuits / 7

9 2. Explain that in each case, the electricity travels through the wires, battery, and bulb only when there is a complete, connected pathway. This is called a closed circuit. Ask participants if they tried configurations that didn t work, and have them demonstrate. Then explain that when the wire is connected to each end of the battery but bypasses the bulb (which will not light), this is called a short circuit. With a small battery such as this, there is no real danger, but the battery and the wire may get warm and the battery will be quickly drained of power. PART 2: How can you make a motor run? PURPOSE: to build a circuit to run a small motor using just a battery. A. Challenge participants to make the motor run. 1. Ask participants to connect the battery and motor in a way that will make the motor turn. Have them draw a picture of their successful circuit. TIP: Suggest that participants put a small piece of paper or tape on the motor shaft so that they can easily see when it is turning. JOURNAL PROMPT Draw and label a picture of the circuit you built to make the motor run. B. Discuss the findings. 1. Invite several students to demonstrate their successful circuits and talk about how the electricity is traveling. How is this similar to the circuit they built with the light bulb? 2. The motors are great fun to experiment with. Give students some time to explore the possibilities of the motors to do work. They may invent fans, propellers, or spinning discs that create optical illusions. CLEAN UP Participants should return their equipment to the storage containers and stow the containers neatly away. Remind them that all circuits need to be taken apart in order to keep the batteries fresh. Project ASK Electric Circuits / 8

10 ELECTRIC CIRCUITS SESSION 3: Designing New Circuits BIG IDEAS Participants have built simple circuits using their hands to connect all the parts. Now they add more equipment to make it easier: bulb holders and battery holders. This allows them to build more complex circuits by combining equipment and sharing ideas. Figuring out how to make a bulb light and how to cause an electric motor to turn will engage students in creating some configurations of wires, batteries, bulbs, and motors that work, and others that don t work. The trial and error associated with this activity will be most useful if both the successes and failures are well documented, along with student ideas about the phenomena they observe. MATERIALS For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 2 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder 1 motor PREPARATION 1. Set out the storage containers for students to pick up. 2. Add battery holders and bulb holders to the supply table and have students put one of each into their storage containers. Project ASK Electric Circuits / 9

11 ACTIVITIES PART 1: What other kinds of circuit designs might work? PURPOSE: to use bulb and battery holders and to work cooperatively to design more complex circuits. A battery holder A bulb holder A. Introduce the bulb and battery holders. 1. Have students form small teams so that they can combine their equipment and their ideas. 2. Give students time to figure out how to build simple circuits using the battery and bulb holders. That is, have them substitute the holders for their hands and replicate lighting the bulb and making the motor turn in two separate circuits. Here is another place where students who have had experience with the Electric Circuits unit may coach their peers. B. Design your own circuits. 1. Ask the teams to work cooperatively to hook up new circuits that use the bulb and battery holders. They may combine their equipment any way they like to experiment. Project ASK Electric Circuits / 10

12 2. Have participants record some of their new creations in their notebooks. JOURNAL PROMPT Draw a picture of the new circuits you built with your team. C. Demonstrate. 1. Give each team the opportunity to show off their best circuit design and to talk about how it works. Encourage students to describe the pathway (closed circuit) that the electricity follows around the circuit. CLEAN UP Ask participants to return their equipment to the storage containers and stow the containers neatly away. Remind them that all circuits need to be taken apart in order to keep the batteries fresh. Project ASK Electric Circuits / 11

13 ELECTRIC CIRCUITS SESSION 4: Designing New Circuits BIG IDEAS A switch is a device for making and breaking the connection in an electrical circuit. When the switch is in the on position, the circuit is closed and electricity flows. When it is in the off position, the circuit is open, and electricity cannot flow. Students are challenged to invent a way to insert an on/off switch into a circuit that they have built. They are also asked to describe verbally the switch and how it works, then to write a description of the switch and instructions for constructing additional switches. MATERIALS For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 2 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder 1 motor For the group 1 roll of masking tape 1 roll of aluminum foil Project ASK Electric Circuits / 12

14 PREPARATION 1. Build a circuit with one bulb, three wires, and one battery as shown below: Touch the ends of the two wires together as shown to make sure the circuit works. This is a kind of manually operated switch. When touching, the wires make a complete circuit and the bulb is lit. When not touching, the circuit is open and the bulb is off. 2. Set out all materials in the distribution center for students to pick up. 3. For the discussion in Part 1, locate several different switches in the room that you can operate. A closed circuit Project ASK Electric Circuits / 13

15 ACTIVITIES PART 1: What does a switch do? PURPOSE: to discuss the function of a switch in an electric circuit. A. Discuss what a switch does. 1. Flip a lamp or an appliance off and on several times. Then ask: What did I use to turn the electrical appliance off and on? (a switch) How do you think a switch works? What does it do? It might be helpful to remind students what they have already found out about open and closed circuits. Then ask them to relate that idea to a switch. B. Demonstrate a simple switch. 1. Show the group the simple circuit that you have made. Connect and disconnect the circuit several times by touching and separating the two wires. Ask: What is happening when I open the circuit? (The bulb does not light. It is like when the switch is off.) What happens when the light goes on? (The circuit is closed, like when the switch is turned on.) 2. This is an example of a very simple but slow switch, and it takes two hands to do it. Challenge students to find ways to open and close a circuit quickly, or one that they could operate with one or two fingers. PART 2: Building a switch PURPOSE: for participants to build a switch and record their findings. A. Make a plan. 1. With their partners, have participants make a plan for building their own switch. Let them know that they may use the masking tape and the aluminum foil in their designs. In addition, invite them to make use of other materials such as pennies, paperclips, cardboard, and wires to which they may have access. Project ASK Electric Circuits / 14

16 B. Build a simple switch. Record the design in the science notebook. 1. Have participants implement their plan to build a simple switch. 2. Remind them to record their design in their notebooks. JOURNAL PROMPT Draw and label your switch. Describe how the switch works. Write instructions to tell someone how to construct a switch. C. Demonstrate. 1. Give each team the opportunity to demonstrate their switch and describe how it works. CLEAN UP Participants should return their equipment to the storage containers and stow the containers neatly away. Remind them that all circuits need to be taken apart in order to keep the batteries fresh. Project ASK Electric Circuits / 15

17 ELECTRIC CIRCUITS SESSION 5: Circuit Diagrams BIG IDEAS Engineers and electricians make use of circuit diagrams both to read and to illustrate electrical circuits. Circuit diagrams consist of electrical symbols that students will learn about and then use to draw the circuits they build. The diagrams are a practical short cut and save lots of time and drawing once students learn to use them. MATERIALS: For each participant 1 science notebook For demonstration 2 batteries 2 bulbs 3 wires 2 battery holders 2 bulb holders For the group Chart paper and markers (for drawing symbols and for illustrating circuit diagrams) PREPARATION: 1. Become familiar with the symbols used for circuit diagrams as shown in the chart on the next page. 2. Copy the symbols onto a large piece of chart paper for students to see. Note: As alternatives to drawing the symbols on chart paper, you may want to either photocopy the symbols and give one sheet to each participant or make an overhead to project for the group. 3. Set up a simple circuit to use in the demonstration in Part 1. For example, you could construct a circuit with two batteries, one bulb, and three wires. Have a second bulb ready to connect into the circuit. Be prepared to use the symbols to diagram the circuits. See the diagrams in Part 1 for illustrations. Note: For convenience, you will want to use the bulb and battery holders too. When drawing the circuit diagram, the holders either are not shown or are represented only as dots when they are connection points between wires. Project ASK Electric Circuits / 16

18 Symbols used in circuit diagrams Project ASK Electric Circuits / 17

19 ACTIVITIES: PART 1: Learning a Secret Language PURPOSE: to learn to read the symbols used in circuit diagrams A. Demonstrate how to use symbols in circuit diagrams. 1. Show participants the simple circuit you have prepared and ask them to name the parts. Then have them find the symbols for those parts (bulb, wire, and battery) on the chart you have drawn up. Discuss each symbol. Let participants know that these are the symbols that electricians and electrical engineers use to draw circuits. 2. Using the symbols, draw the circuit diagram showing one bulb, two batteries, and three wires. It should look something like this: Circuit diagram showing one bulb, two batteries, and three wires Project ASK Electric Circuits / 18

20 3. Demonstrate a second circuit. This time take out one battery but add another bulb to the circuit. Have participants direct you in drawing the new circuit diagram. It should look something like this: Circuit diagram showing two bulbs, one battery, and three wires Keep these diagrams to refer to in the next session. 4. Tell students that from now on they can use this secret language to record their circuits. They will appreciate how much simpler this will make their record keeping. PART 2: Building a switch PURPOSE: for participants to build a switch and record their findings. A. Make a plan. 1. With their partners, have participants make a plan for building their own switch. Let them know that they may use the masking tape and the aluminum foil in their designs. In addition, invite them to make use of other materials such as pennies, paperclips, cardboard, and wires to which they may have access. B. Build a simple switch. Record the design in the science notebook. 1. Have participants implement their plan to build a simple switch. 2. Remind them to record their design in their notebooks. Project ASK Electric Circuits / 19

21 JOURNAL PROMPT Draw and label your switch. Describe how the switch works. Write instructions to tell someone how to construct a switch. C. Demonstrate. 1. Give each team the opportunity to demonstrate their switch and describe how it works. CLEAN UP Participants should return their equipment to the storage containers and stow the containers neatly away. Remind them that all circuits need to be taken apart in order to keep the batteries fresh. Project ASK Electric Circuits / 20

22 ELECTRIC CIRCUITS SESSION 6: Series Circuits BIG IDEAS Participants will learn about two different types of circuits: series circuits (in this session) and parallel circuits (in Session 7). In a series circuit the component parts are arranged so that electricity flows through all points in a continuous loop. If any part of the loop is opened, the electricity ceases to flow. In a series circuit, any break in the continuous pathway will act like a switch and interrupt the flow of electricity. In constructing a variety of circuits, participants will also become aware of differences in brightness related to the number of batteries or bulbs in the circuit. Generally, two batteries will cause one bulb to glow more brightly, but the batteries will die more quickly. MATERIALS For the group 2 circuit diagrams created in Session 5 For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 4 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder 1 motor PREPARATION 1. Display the pictures of the circuit diagrams you created for Session 5. Project ASK Electric Circuits / 21

23 ACTIVITIES What is a series circuit? PURPOSE: to learn to identify a series circuit and explore its characteristics A. How does electricity flow in a series circuit? 1. Focus attention on the circuit diagrams you created with the class in the last session. Ask for a volunteer to come up to one of the diagrams and trace the path of electricity in the circuit. Have the group notice that the electricity has only one pathway to travel. The pathway is a continuous loop with no breaks. Electricity flows through all points along the loop at the same time, as long as the circuit remains closed and everything stays connected. There were no choices or crossroads along the way. This is a series circuit. As reinforcement, repeat the activity with the second diagram. 2. Have participants look at their journal entries from Session 5. Ask: Can you find examples of series circuits in your circuit diagrams? How do you know they are series circuits? Have several participants show their series circuits to the group. 3. Challenge students to construct series circuits of their own design following their diagrams. If they need to modify their circuit diagrams or construct new ones because they hadn t designed a series circuit, have them do that first. Let them know that they may combine their equipment to add more bulbs or more batteries to the circuit in any order they wish. JOURNAL PROMPT With your partner, construct one or two series circuits. Follow your circuit diagrams. Draw diagrams of any other new circuits that you construct. What happens when you use more than one battery? What happens when you use more than one bulb? What happens if you unscrew one bulb? Note: A team may inadvertently construct a parallel circuit. If this happens, ask them to save it for the next session. Project ASK Electric Circuits / 22

24 4. Discuss what participants found out. Have them demonstrate some of their circuits and trace the flow of electricity. Participants will find that in a series circuit, any break in the continuous pathway (such as unscrewing one bulb) will act like a switch and interrupt the flow of electricity. 5. Let participants trade circuit diagrams. Can someone else build the same circuit by following the diagram? Project ASK Electric Circuits / 23

25 ELECTRIC CIRCUITS SESSION 7: Parallel Circuits BIG IDEAS In the last session, participants worked with series circuits. Now they will learn about another type called parallel circuits. A circuit showing batteries wired in parallel In a series circuit, electricity can only flow along one continuous pathway, and any break in the pathway interrupts the flow of electricity. In a parallel circuit, electricity flows to individual branches and there is more than one possible pathway. A break in one pathway acts as a switch to cut power to that part of the circuit, but other branches continue to receive power. Project ASK Electric Circuits / 24

26 MATERIALS For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 4 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder 1 motor For the group Chart paper and markers PREPARATION 1. Make a large drawing of the diagram of the parallel circuit shown on page 23. ACTIVITIES What is a parallel circuit? PURPOSE: to learn to identify a parallel circuit and explore its characteristics A. How does electricity flow in a parallel circuit? 1. Show participants the drawing you have made of a parallel circuit (see Preparation). Ask: What is in the circuit? (two bulbs, one battery, four pieces of wire). What does the symbol with a large black dot mean? (two wires are connected) Note: If a team constructed a parallel circuit in Session 6, use it now as another example. 2. Tell participants that this is a different kind of circuit called a parallel circuit. Then have a volunteer trace the possible pathways of electricity in the parallel circuit. Ask: How are these pathways different from the pathway in the series circuit? Where are the crossroads? Where do you have to make choices? Project ASK Electric Circuits / 25

27 3. Using the circuit diagram, have teams of students work together to construct the parallel circuit as illustrated on the chart. Provide coaching or let students who have experienced the Electric Circuits unit team with those having difficulties. 4. When everyone has successfully constructed one parallel circuit, encourage them to go on with further constructions of their own design. Provide some prompts as below. JOURNAL PROMPT With your team, construct one or two parallel circuits. Draw your circuits using the circuit diagram symbols. What happens when you use more than one battery? What happens when you use more than one bulb? What if you unscrew one bulb? What if you disconnect one wire? 5. Discuss what participants found out. Ask: How are series and parallel circuits alike? How are they different? Project ASK Electric Circuits / 26

28 ELECTRIC CIRCUITS SESSION 8: Switches and Circuits BIG IDEAS Participants put together what they already know about series and parallel circuits and about switches. They make predictions about what they think will happen if a switch is placed in different locations in each type of circuit. Then they build the circuits to test their predictions, and record the results. This lesson offers a good opportunity for participants to synthesize their knowledge and to apply what they have learned to new situations. MATERIALS For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 4 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder 1 motor For the group 1 roll of masking tape 1 roll of aluminum foil Chart paper and markers PREPARATION 1. Prepare a large sheet of chart paper. Divide it into three columns. Label the first column Type of Circuit, the second Predictions, and the third Test Results. Project ASK Electric Circuits / 27

29 ACTIVITIES What does a switch do? PURPOSE: to observe how a switch works in different locations in both series and parallel circuits A. Make predictions. 1. Review the purpose that a switch serves. Ask participants to describe how they constructed switches in previous sessions and tell how the switches worked. 2. Then ask participants to make some predictions. How do they think a switch will work when added to either a series or a parallel circuit in different positions? Use some of their circuit designs to talk through the predictions, asking what they think would happen if a switch were added here or there. Record their predictions on the chart you have prepared. B. Test the predictions and record results. 1. Challenge participants to test their predictions. Working in teams, have participants construct both series and parallel circuits. Then have them add a switch first in one location and then others. Encourage them to record their findings. JOURNAL PROMPT Construct a series circuit and a parallel circuit. Draw your circuits using the circuit diagram symbols. Add a switch to each of the circuits. Move the switches, batteries, and bulbs around to different places in the circuits to see what happens. Record your test results. Project ASK Electric Circuits / 28

30 C. Analyze the test results. 1. Ask participants to present their best findings. They can use their electrical equipment to demonstrate and also show their circuit diagrams to the group in case others want to try them out. 2. Record test results on the chart. Here is a summary of possible findings: Participants will find that in a series circuit, any break in the continuous pathway will act like a switch and interrupt the flow of electricity. In a parallel circuit, the flow of electricity to the individual branches of the circuit can be controlled with switches. The effect of stopping electricity in one branch has an effect on the amount of electricity in another branch. They may also find that a short circuit can create a pathway for electricity that robs other branches of the current needed to light a bulb or turn a motor. Finally, they will likely discover that the order in which the circuit elements are placed does not affect the amount of electricity that flows in any one series or branch circuit. Project ASK Electric Circuits / 29

31 ELECTRIC CIRCUITS SESSION 9: Conductors and Insulators BIG IDEAS Participants carry out a series of tests to determine what kinds of materials can be used in place of the plastic-coated wire introduced in previous sessions. They will find that some materials allow electricity to pass easily through them. These are called conductors. Materials that do not allow electricity to pass easily through them are sometimes used as insulators. SAFETY NOTE Under certain circumstances and if the voltage is high enough, all materials conduct electricity at some level. Even the human body will conduct electricity, and this may result in a dangerous shock that can disrupt heart function and cause burns. So we need to protect our bodies from conductors that carry electricity. An electrical cord is a good example. The wires that conduct electricity are hidden inside the cord, covered with a plastic coating that protects us from coming in contact with the electric current. MATERIALS For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 4 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder 1 motor For the group Aluminum foil Pipe cleaners Paper clips Pencils Rubber bands Magnetic tape Drinking straws Chart paper and markers Project ASK Electric Circuits / 30

32 PREPARATION 1. Set out the materials in the distribution center. 2. Construct a circuit tester. See the illustrations below. A circuit tester with two ends touching. The bulb will light. Testing a paper clip to see if it closes the circuit. 3. Prepare a chart to record test results. Please see Part B for a suggested format for the chart. Project ASK Electric Circuits / 31

33 ACTIVITIES What are conductors and insulators? PURPOSE: to carry out a series of tests to determine what kinds of materials conduct electricity well or conduct electricity poorly A. Demonstrate a circuit tester. 1. Show participants the circuit tester that you have built. Then ask them to make predictions. Ask: What do you predict will happen when I touch the two ends of the wires together? (The light will go on.) Explain why that happens. (The circuit is closed and electricity is flowing through it.) 2. Ask participants to think about how they can use the tester to find out if other objects like a paper clip can be part of the circuit and let electricity flow through them. Accept all suggestions, and use the tester to find out how well the paper clip conducts electricity. 3. Then ask participants to predict what will happen if you substitute a rubber band for the paper clip in the circuit. Will it let electricity flow? How will you know? (If the rubber band conducts electricity well, the bulb will light. If it doesn t, the bulb will not light.) Project ASK Electric Circuits / 32

34 B. Carry out tests to find conductors and insulators. 1. Challenge participants to test at least ten objects and find out if they are good or poor conductors. They may use objects from the supply table that you have laid out or other objects of their own choosing such as coins, fabric, jewelry, furniture, windows, and chalk. Remind them to record their experiments on a chart such as the one shown here: JOURNAL PROMPT Name of Object Prediction Result SAFETY NOTE Warn participants never to put the wires into an electrical outlet. C. Analyze the test results. 1. Focus attention on the chart you have prepared to record test results. Ask volunteers to report on their results and record these on the chart. If there are conflicting results, ask participants to repeat the test. Ask them to draw general conclusions about what kinds of materials allow for good conductivity and what kinds do not. Project ASK Electric Circuits / 33

35 2. Briefly discuss the ways we might use conductors and insulators when dealing with electricity in our daily lives. Ask: What are some ways in which insulating materials are used to make electricity safer to use? Participants might mention, for example, that plastic is used to coat the two wires in an appliance cord to prevent a short circuit and possible fire. TIPS ON PREPARING FOR THE LAST SESSION Let participants know that for their final activity they will be designing and building a flashlight. Encourage them to start thinking about how it will operate, and to bring in any additional materials (such as parts of discarded toys, plastic drink bottles, and cardboard tubes) they might want to use in the construction. Project ASK Electric Circuits / 34

36 ELECTRIC CIRCUITS SESSION 10: Making a Flashlight BIG IDEAS Participants develop a plan to design and construct a flashlight and then carry out their own plan. In the process, they will have to use what they have already learned about circuit diagrams, series and parallel circuits, insulators and conductors, and switches. This unit lends itself especially well to demonstrations. Take advantage of this feature to plan a culminating event in which participants can give demonstrations to a wider audience and share the exciting discoveries they have made. MATERIALS For each participant 1 science notebook 1 storage container with 1 D-cell battery 1 bulb 4 6-inch pieces of wire (15 cm) 1 battery holder 1 bulb holder For the group Aluminum foil Paper clips Construction paper Scissors Masking tape Crayons or markers Chart paper Project ASK Electric Circuits / 35

37 PREPARATION 1. Several days ahead of time, remind participants to bring in materials they want to use to build their flashlight. 2. Set out all the materials in the distribution center. 3. Hang up a piece of chart paper and label it Parts of a Flashlight. ACTIVITIES PART 1:What s inside a flashlight? PURPOSE: to figure out the component parts of a flashlight A. Discuss the parts that make up a flashlight. 1. Ask participants to list the parts that they think are necessary to make a flashlight. Have them give a reason for including each part. For example, they might say the flashlight needs batteries for a source of power or a switch to turn it on and off. 2. Record their ideas on the chart you have prepared. Participants will probably list the following parts: Batteries A bulb Wires or other conductors A switch B. Design a flashlight. 1. Working with a partner, have teams draw up a design for a flashlight they could make using the materials available. Show them the table of supplies you have set out for their use and remind them that they can combine materials from both of their storage containers. Encourage them to supplement their supplies with materials they have brought in, such as plastic drink bottles, cardboard tubes, and parts from discarded toys. 2. Have participants record their design in their notebooks. Remind them to use circuit diagrams. Project ASK Electric Circuits / 36

38 JOURNAL PROMPT Make a plan to construct a flashlight. Draw your plan using a circuit diagram. C. Build a flashlight. 1. Have teams follow their own plans to build a flashlight. They may need to modify their plans along the way, and this is fine. 2. Give each team the opportunity to show their flashlight to the group and to explain how it works. PART 2: Show others what we have learned. PURPOSE: for participants to share their discoveries with a wider audience A. Plan a culminating event. 1. With the group, plan an event to bring the electricity unit to an enjoyable and satisfying conclusion. They may suggest sharing their discoveries with another group, inviting parents or caregivers, or sharing their work with their in-school class. 2. Have students plan their presentations. They may want to demonstrate some of the activities they most enjoyed, such as constructing different kinds of circuits or designing a flashlight. B. Enjoy the event! 1. Give participants the opportunity to showcase their talents and share what they have learned with others. Project ASK Electric Circuits / 37