Overview

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

Advance preparation

• Make five sample hidden switches -- see a video and diagram illustrating each one;
• Photocopy worksheet and assessment (downloadable at bottom of page);
• Post a sheet of chart paper to debrief Hidden Switch Hunt, with columns labeled "Found where?" "Controls what?" and "Operates how?"
• Post a sheet of chart paper for brainstorming Ideas for Gadgets.

Materials

• As in previous lessons: Motors, buzzers, bushings, wheels, LEDs, buzzers, coin batteries, hook-up wire, wire strippers, paper fasteners, paper clips,rubber bands, tape, cardstock, scissors, tape, craft supplies
• Additional materials: clothespins, cardboard boxes
• Five sample hidden switches

Procedure

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.

Troubleshooting

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;
• A light-up card whose LED turns on when the book is closed;
• An alarm clock that buzzes when pressed from behind; the same idea can be used to make a squeeze-me toy:
• A wind alarm that buzzes when it is breezy;
• A color wheel that spins when a box is opened;
• A light box: close the box and see the light through the peep hole;
• A buzz box, which buzzes when closed;
• An airplane or helicopter: the proller starts turning when the box is closed;
• A seat-controlled car horn, which sounds when you lean back on the seat; and
• An upside-down alarm, which goes off when the box is turned upside-down.

Worksheet: Make a Gadget

Assessment