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ELECTRIC CIRCUITS
Grades 7-9

Overview

This lesson defines electricity and describes the parts of a simple circuit, detailing how to assemble a circuit and introducing the vocabulary necessary to discuss electric circuits. Using equipment demonstrated in the video the students will build and test electric circuits. They will then build a circuit tester and use it to infer the wiring inside a "black box".
ITV Series
Electricity and Magnetism, #2: Creating and Controlling CURRENT ELECTRICITY
Learning Objectives
Students will be able to:
Materials
Each student lab group needs:
Vocabulary
Pre-Viewing Activities
Divide the class into lab groups and have each group obtain a packet of lab equipment from the materials list above.
Focus Viewing

The focus for viewing is a specific responsibility or task(s) students are responsible for during or after watching the video to focus and engage students' viewing attention. Divide the class into six groups. Give them drawing paper and pencil or pen. Give each focus group one of the tasks listed and tell them that after the tape they will be asked to present their question and answer in front of the class. Remind them that they may ask for the tape to be rewound and replayed as needed.

Why are metals good conductors? Use diagrams or drawings to assist you.

Why is plastic not a good conductor? Use diagrams or drawings to assist you.

What is a complete circuit? Use diagrams or drawings to assist you.

How does a wet cell battery work? Use diagrams or drawings to assist you.

How does a dry cell battery work? Use diagrams or drawings to assist you.

Viewing Activities
BEGIN playing the video from the opening credits. PAUSE the video when the narrator says "We'll start things off by touching the wires to a bulb socket." and the screen shows a boys hands touching two wires to a bulb socket.

Have your students assemble a similar circuit and test it using the equipment in their lab packet.

RESUME playing the video and PAUSE when the narrator says "Scientists call such movement of electrons an electric current." and the screen shows a boy attaching a wire to the top of the battery.

Check for comprehension by asking "What is an electric current?"

RESUME playing and PAUSE when the narrator says ". . . by attaching one of our wires to this plastic pocket comb." Be sure you STOP the tape before the boy touches the comb to the lamp socket.

Have the student predict what will happen. Then have the students perform the experiment with the equipment in their lab packet.

RESUME playing the video and PAUSE when the narrator says ". . . such as plastic through which current does not pass." The screen should still show a bulb socket with the word Insulator under it.

Have students predict which items remaining in their lab packet are insulators and which are conductors. Have them record their predictions on the data table. They should then test each item and record their results.

FAST FORWARD the video to the scene where the camera does a close-up of a girl touching a silver spoon to the lamp socket and RESUME playing. PAUSE when the picture of a girl with a simple circuit blurs and the narrator says ". . . in ours the useful device is a light bulb." FAST FORWARD the video until the screen shows hands holding a red battery tester to a blue and gold battery. RESUME playing. STOP the video at the end of the tape.
Post-Viewing Activities
Have each group present their focus for viewing task to the class. Facilitate questioning of the groups by the students watching.

Have the students do the lab activity "Inferring a Wiring Diagram". All the equipment that they will need is in their lab packet. Plans are included to create the "black boxes" for testing purposes. Build enough black boxes so that each group may test two.
Action Plan
Have an electronic technician or electrician visit the class and discuss wiring and circuits related to their work.

Have the students prepare a demonstration of electric circuits to present to class of younger students.

Have the students bring in wiring diagrams from old car repair manuals, TV/VCR repair manuals, etc. for display and discussion.

Take students on a field trip to a power plant or battery recycling center. Have them prepare photo or video reports on their trip.

Write to the local utility companies and find out how electricity production and usage has changed over the last 10 years.
Extensions
Science, Language Arts, Graphic Arts and Social Studies: Have students prepare reports on famous electrical experiments using diagrams or posters and video taping their presentations. For example: Milliken's oil drop experiment, Ben Franklin and the key, Thomas Edison and his several electrical products, Tesla and the Tesla coil, the invention of the Leyden jar, the Van de Graff generator, etc.

Science and Math: Using house plans and maps as resources, calculate the amount of wiring needed to wire a room, or a house, or a block, or a neighborhood.

Science and Social Studies: Have students research the spread of rural electric cooperative in the U.S. and discuss how electrification changed the lives of the people living in remote areas. Have them compare the lifestyles of rural persons in the 30's and 40's with the lifestyles of urban dwellers in the same time frames.

LAB ACTIVITY -- INFERRING A WIRING DIAGRAM

Purpose: Infer the circuit wiring of a device by building a simple circuit tester and testing the device.

Materials: Use the lab packets described in the lesson Electric Circuits.

Before you begin, obtain your materials, select a recorder for your group and record your names on a page to contain your data.

First, discuss with your group how to build a circuit tester using the wires, socket and battery. Record a description or labeled diagram of your device.

Second, plan with your group how you could use your circuit tester to find out how the electrodes are wired together inside the Circuit Testing Boards. Record your test plan.

Third, conduct your test according to your plan. Record all of your results. (Hint: record both the positive results [the bulb lights] and the negative results [the bulb does not light].

Fourth, using your test data, draw a circuit diagram of how the wires are connected to the electrodes inside the device.

CREATING YOUR OWN BLACK BOXES

MATERIALS 24 cardboard triangle (about 5 inches on each side) 120 brass paper brads 50 - 100 jump wires (short pieces of wire stripped at both ends) 1 roll of electrical tape

On 10 of the cardboards punch 10 holes in the pattern of standing bowling pins and insert the brass brads. Use the jump wires to attach pairs of brass brads together on the back of the board. Some brads should be used twice and some not at all. Label each brass brad with a number on both the front and back and copy the wiring diagram for that board. Tape a cardboard triangle to that board securing the tape around all the edges to keep students from being able to take the back off or to see the wires.

Master Teacher: Joyce M. Conner

Worksheet
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