## Three Switches

### T. SundeenOrange County Schools

#### Description

Students will discover three types of electrical switches and form connections to their lives with examples that they generate.

#### Objectives

The student knows how to trace the flow of energy in a system (for example, electricity in a circuit to produce heat, light, sound, or magnetic fields).

#### Materials

-Large screen television (The large screen TV and computer can be substituted with an overhead projector and transparencies.)
-Computer
-Computer program showing different types of circuits and switches (Computer program -Crocodile Clips for Elementary Students- http://www.crocodile-clips.com/m6_4.htm)
-Dry erase markers (for writing on TV or chalk board)
-Worksheet with ten examples of types of switches (created from Crocodile Clips)

#### Preparations

Clips for Elementary Students- http://www.crocodile-clips.com/m6_4.htm)
- Create a worksheet using screen shots from Crocodile Clips
-Be sure to have several colors of dry erase markers on hand to illustrate circuits on the chalk board
-Circuits can also be drawn simply by using Microsoft Paint or a similar program.

#### Procedures

Prerequsite Learning:

Students should have been exposed to the fundamentals of electrical circuits and understand the concepts of a completed circuit, incomplete circuit, and power source.

Body:

1. Use the large screen TV and computer program to show a simple circuit without a switch. Ask students if this is an open or closed circuit.

2. Have students describe the parts of the circuit.

3. Show the second circuit with a simple toggle switch. Ask students to identify the purpose of the switch. Describe the purpose of the switch. Reinforce the concept and transfer of knowledge by asking questions such as:
Where else have you see a switch that works like this? (Answer: You might use it at home to turn on and off the lights.)

4. Display a circuit with a push-button switch. Describe how it works and ask the class: Has anyone ever used a switch like this before? Possible answers can include a doorbell or a button on a stereo.

5. Display a circuit with a variable resistor and demonstrate how the light becomes dimmer or brighter as the sliding resistor is moved back and forth. Tell the students that this is like a water faucet. When you turn it on a little, you get just a little electricity. When you turn in on more, more power flows, just like the water in your sink at home. Probe the students for some ways that a device like this might be used. Possible answer can include the volume control on a stereo, a ceiling fan control, or a variable light control at home.

Guided Practice:

1. Instruct the students to take out a piece of paper and pair up with the person to their left.

2. Model for the students the separating of their papers into three columns by drawing two lines vertically on the paper.

3. Ask the students to write the words toggle switch, push button, and variable resistor above each column.

4. Tell the student that they have five minutes to write down as many uses for each type of switch in each column that they can think imagine.

5. Check for understanding by moving about the room and helping students with their lists.

Closing:

Review with the students by saying: We have seen three ways to control an electrical circuit; a toggle switch, a push button, and a variable resistor. We have also seen how often we use these in our everyday lives and how important they can be to us.

#### Assessments

1. Probe for understanding with lower order questions.
· What kind of switch is this? (toggle, push button, variable resistor)
· What is a circuit? (an complete circle formed with wires and a power source)
· Show me the power source. (identify a battery)
· Is this circuit open or closed? (refer to model)

2. Probe for understanding with higher order questions.
· What will happen to the light (or buzzer) if we open the circuit? (It will turn off.)
· How could you know if a circuit is closed? (The light would be on.)
· Where would you use a switch like this? (Answers will vary)

3. Observe discussion of students paired together for cooperative worker skills. Correct the student worksheet as a class.
Answering 80% of the worksheet questions correctly will meet mastery requirements for the Sunshine State Standard.