Students share the results of their home Switch Hunt. They looked for electrical switches and what they control. They categorized the action needed to operate them: push button, slide, toggle and rotary switches. Students discuss the reasons for including a switch in a circuit. They then design and create as many types of switches as they can. Each student places a switch in a circuit so that it controls a motor.
The class reviews the Switch Hunt worksheets they completed at home. Here are ideas for this review. Ask students:
What is a switch?
Where can you find one?
What is the advantage of having a switch over touching two wires together?
Develop the idea that a switch lets you turn a motor (or light) on or off without touching any wires.
How does a switch work?
In order for a switch to work, it has to be in one position for the motor to be ON and in another position for the motor to be OFF. A switch stops the flow of electricity to a load when it is off. It allows electricity to flow through the load when it is on. This means the switch must be placed in a circuit in such a way that all the electricity that flows through the load must also flow through the switch. See this video. On a drawing of a circuit with a battery and motor, ask:
Make a switch:
Explain that students will make their own switches. Ask them:
Add your switch to a circuit: The next challenge is:
Sorting switches by action needed to operate them:
After students have made switches and gotten them to work, gather the class to think about types of switches, according to the action you take to operate them. The most common types are rotary, toggle, push-button and slide. Ask students:
Most of the problems students have is with bad connections. These are connections that do not allow current to flow from one circuit element to the next. Here are videos of two common problems.
Here are analyses and solutions to other common problems.
Here is what to look for if the connections are all good and the motor still doesn’t run.