Students often love science projects, especially when they illustrate intangibles like conductivity. Creating conductive liquids shows students that materials with a certain chemical make-up conduct electricity. Mixing up your own electrically conductive liquid shows how electrons move through materials. After the experiment, students discuss what they discovered, cementing the concepts in their memories.
Fill a large glass jar with about a pint of warm vinegar. You may heat the vinegar in the microwave or simply set it in the sun for an hour or two. It doesn't have to be boiling hot, just warm to the touch.
Add 1/4 cup of salt to the vinegar. Stir the mix with a long wooden spoon until the salt dissolves completely. The salts present in the vinegar plus the additional salt should create a very conductive liquid.
Set two 9-volt batteries side-by-side so the positive terminal of one and the negative terminal of the other are facing up. Wrap a piece of electrical tape around the middle of the batteries, securing them together.
Place a steel paper clip across the positive terminal of the right battery and the negative terminal of the left battery, positioning it like a bridge across the batteries. Tape it down with another piece of electrical tape. Flip your new battery pack over so you can see the other end of both batteries. Tape the end of an alligator clip wire to each remaining terminal.
Dangle the loose end of one alligator clip wire into the vinegar solution. Clip the loose end of the other wire to one of the clips on your light bulb holder. These flat, plastic light sockets hold low-watt light bulbs for science experiments.
Clip a third alligator clip wire to the second clip on your light bulb holder and dangle the other end of the wire in the vinegar solution. This should complete the circuit and make the light bulb glow.
Try different solutions like ordinary water, water and salt, vinegar alone, vinegar with sugar and salt with sugar. Discuss what happens with each solution.