This is the fourth Investigation of the LabLearner CELL Exploring Electricity. In it, students learned about electrical conductors and insulators.

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A. Begin the analysis of the Lab by helping students recall the experiments they conducted.  The following questions may be helpful in prompting student discussion:

1. Ask students: Can you recall the four main questions that you investigated in the Lab? Students were asked the following questions:  Which materials act as conductors of electrical current?  Which materials act as insulators of electrical current?  Are some conductors better than others in conducting electrical current?  Can you predict whether a material is a conductor or insulator?

2. Ask students: Can you describe what you did in your experiments to answer the questions? Students should suggest that to answer the first three questions several different materials were placed into a simple circuit.  Students then determined whether the new circuit was a complete or incomplete circuit.  To answer the fourth question, the properties of the several selected materials were observed and a prediction was made about whether each material was a conductor or an insulator.  The materials were then tested.

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B. Continue the analysis of the Lab experiments by using the following questions to initiate a discussion with the students.  Students may wish to refer to their Student Data Record during the discussion.  Ask them: 

1. Ask students: How did you use the simple circuit you built to test the materials? Students should indicate that they positioned the item to be tested between the two wires with free ends, then touched those wires to opposite sides of the item.  Students then observed whether the bulb in the circuit remained unlit or was illuminated.

2.  Ask students: Which materials were conductors of electrical current?  How did you know? Students should indicate that the paper clip, metal cube, and lab scoop were conductors because the light bulb glowed.  Students may also indicate that the pencil was a conductor if the metallic part that holds the eraser in place was used during their tests of the circuit.

3. Ask students: Why did the light bulb glow when the material you tested was a conductor? Students should indicate that the conductor allowed electrons to flow through the circuit.  Because the material was a conductor, electrons could move from the negative end of the battery, through the wire and item tested to the opposite wire, and to the positive end of the battery.  Materials that were conductors resulted in the formation of complete circuits.

4. Ask students: Which materials were insulators of electrical current?  How did you know? The cotton ball, small bear, glass stir rod, moon ball, and woodblock were insulators because the light bulb did not glow when the item was tested with the simple circuit.  If students tested the wood or the eraser portions of the pencil they should conclude that these portions were insulators.

5. Ask students: Why didn’t the light bulb glow when the material you tested was an insulator? Students should indicate that the insulator prevented the electrons from flowing through the circuit.  Because the electrons could not move through the material, an electrical current could not flow through the circuit.  The inclusion of insulators in the circuit produced an incomplete circuit.

6. Ask students: Why could you consider the pencil both an insulator and a conductor of electrical current? The pencil could be considered both an insulator and conductor depending on which parts of it were included in the circuit.  Some portions, such as the metal cylinder, conducted electricity.  Other portions, such as the wood shaft or rubber eraser, insulated against electrical current.

7. Ask students: In Trial 2, what did you discover when the paper clip, metal cube, lab scoop, and metal portion of the pencil were retested?  Was there a difference in the glow of the light bulb?  What conclusions can you draw from these observations? Yes.  The light bulb glowed brighter and was steadier (didn’t blink on and off as much) when testing the metal cube and paper clip than when testing the lab scoop and metal part of the pencil. These observations suggest that the metal cube and paper clip were better conductors of electricity than the lab scoop and the metal of the pencil.

8. Ask student: In Trial 3, were successful in predicting which of the items you tested were conductors or insulators? Student answers may vary.

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C. Tell students they will investigate this question further by organizing into the same pairs as they had during the Lab in order to conduct further analysis of their experiments.

1. Instruct student pairs to make two lists.  One list will consist of the materials they tested that were conductors and the other list will consist of the materials they tested that were insulators.  Ask students to record their lists in Problem 5 of the Student Data Record.

2. Explain to students that they should compare the properties of the materials in the two lists to determine if they can discover a pattern that can help them predict whether a material is a conductor or an insulator.  Students should think about properties such as color, size, shape, weight, texture, and what the object is made of.

3. Tell students to study the materials in the two lists.  

Ask students:  What properties can you identify in the materials? Student answers will vary.

4. Allow 10-15 minutes for student pairs to complete their list, and then encourage students to share their observations.  

As students make their suggestions, record them on the board.  Guide students toward identifying shape, color, and composition as properties.  

5. Ask students: Can you find a pattern in the properties? Student answers will vary.

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6. Ask students:  How could we organize the properties to be able to find a pattern more easily? Student answers will vary.  

Guide students toward the realization that a Table can help them discover a pattern.

a. Work with students to develop a Table that will organize their data.  

Use the following questions to prompt students to think about what they may need as they create their table:

• What questions do I need to answer?

• What type of results can help me answer my questions?

• How can I arrange my table to show what I need?

• Should I organize my data in one or two tables?

b. Draw the Table on the board as you incorporate their suggestions.  One example of how the Table can be organized is shown on this slide. 

Teacher Note:  Students will complete a table for the conductors they tested in Problem 6, and then answer several questions about the properties they list for each material.  They will repeat this process in Problem 7 for the insulators.

c. After students have entered the titles into the Table in Problem 6a, encourage them to enter the information into their Table.

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Continue with the construction of a second Data Table organizing the properties of insulators as shown on this slide.

Instruct students to include the results of classroom discussion and Table construction in Problem 7 in their Student Data Record.

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7. Direct students to continue to work in pairs to answer the questions listed in Problem 6b of their Student Data Record.  

Read the questions to the students and then allow them several minutes to analyze the data in the table and record their answers.

a. Are there any properties that are different for all objects?

b. Are there any properties that are similar for all objects?

c. Can you find a pattern based on similar properties?

8. Ask students:  Did you find a pattern in your Table? Students should indicate that all the properties in the tables were different for most of the materials, but they discovered that the conductors were all made of metal.

9. When students complete their answers, encourage them to repeat the same process with the insulators in Problem 7 of their Student Data Record.

10. Ask students:  Did you find a pattern in your table? Students should indicate that all of the objects differed in all of their properties, including composition.  However, students may observe that none of the insulators were made of metal.

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D. Complete the analysis for this Investigation by asking several questions that will summarize the experiments:

1. Ask students: How successful were you in predicting insulators and conductors in Trial 4?  Had you already determined that metal objects are likely to be conductors?  Would you be better at predicting conductors and insulators now?  Why? Student answers may vary.  Students should indicate that they would be better at predicting conductors and insulators of electricity.  Based on their experience in this Investigation, students should be able to predict that an object made of metal is likely to be a conductor and an object that is not made of metal is likely to be an insulator.

2. Ask students: Can you think of examples of items that are both insulators and conductors based on the results of your experiment? Examples students might suggest include extension cords, the cords used to plug in appliances, etc.

3. Ask students: Why do you think a cord acts as both an insulator and conductor? The metal wire inside the cord acts as the conductor, allowing electrical current to flow along a path through the circuit.  The outer plastic coating acts as the insulator, preventing the current from moving to an item other than the wire.  The insulator surrounding the conductor keeps the current moving along a specific path.

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4. Explain that students only tested solids in their experiments.  

Ask students:  Do you think liquids can act as conductors? Student answers may vary.

5. Direct students to think back to the story at the beginning of the Investigation.  

Ask students:  Why do you think Sierra’s mother asked her to take the blow dryer away from the bathtub? Student answers may vary.  

Students may realize that a blow dryer is an electrical appliance.  When plugged into an electrical outlet, a current moves through the cord to the blow dryer.  If the dryer should fall into the bathtub of water when it is plugged into an outlet, an electrical current will move into the water.  

6. Ask students: What does this story tell you about water and electrical current? Students should indicate that water is a conductor of electricity.

7.Ask students: Can you think of any other examples when you need to be careful with water and electricity? Examples students may suggest include being in the water when it is lightening, not standing in a puddle, taking a shower, or putting your hands in water in the sink if an electrical appliance is nearby or if it is lightning.  Students may also suggest that it’s not safe to drop an electrical appliance into water.

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E. To complete this Investigation, tell students they will continue to study two other types of circuits, series and parallel circuits, during Investigation Four.