A hidden switch is one that you operate without seeing it. In this lesson, students discuss the results of the Hidden Switch Hunt done as homework (see Lesson 5), and brainstorm additional examples. Then they make hidden switches, and incorporate them in their own gadgets
1. The Hidden Switch Hunt: Chart examples of hidden switches that students have found as homework. For each one, list where it is found, what it controls and what you have to do to operate it. For example, a refiregerator has a switch that turns on the light when you open or close the door. See Troubleshooting for more examples.
2. Design a gadget: Show students two assembled cardboard boxes -- one of each size -- and a clothespin. They can use these or cardstock to make gadgets that are controlled by hidden switches. What would they like to make? Conduct a brainstorming session to develop and chart a list of possible ideas. See Troubleshooting for some suggestions.
3. How to make a hidden switch: How will they make the hidden switch that will be inside the gadget? Ask students for ideas, and if necessary demonstrate the five sample hidden switches.
4. Make your gadget: Provide time for students to make their gadgets. If students become frustrated, remind them of the discussion about troubleshooting in the previous lesson.
Hidden Switch Hunt: Here are some examples that students may not have listed:
Motion-activated lights in light-up sneakers;
electric pencil sharpener, activated by inserting a pencil;
automobile dome light, controlled by opening or closing a door;
automatic door that opens when someone comes nearby;
automatic faucets, soap dispensers and toilets and hand dryers in public bathrooms;
voice-activated toy, which turns on in response to sound
"Tickle-me" toy, which is activated by pressure;
A car alarm, which turns on when someone comes close to thecar;
Burglar alarm, activated by motion, opening a door or breaking a window;
Automatice street lights, which come on at dusk and go off at dawn;
Energy savers, which turn something off when it isn't being used
Ideas for gadgets: Here is a list of gadgets students have thought of; click on the blue links to see videos of the first five items:
A dollar-bill theft alarm that uses a clothespin switch to protect a dollar bill from being stolen; the same idea can be used to make a cabinet alarm, by tying a piece of cardboard to the door and inserting it in the clothespin;