Science projects that involve building circuits or simple homemade batteries are good tools for teaching students about electronics. Detailed instructions for these and many other electricity projects are available at SteveSpanglerScience.com.
Many ready-to-use circuit-building kits are available for purchase. These kits generally include a battery, insulated wires, a light bulb and a simple switch. Putting these kits together teaches students about complete and incomplete circuits. This experiment can be modified to teach students about conductors and insulators by asking students to attempt to complete an open circuit using a variety of materials. Some of these materials should be conductors, such as iron nails, and some should be insulators, such as rubber erasers.
Students can construct a simple battery using only an ice cube tray, copper wire, five galvanized nails, an LED light bulb and distilled white vinegar. To put the battery together, wrap a piece of copper wire around each nail, leaving a wire tail just below the nail head. Place the wire-wrapped nails into ice cube tray compartments filled with vinegar, and connect them using the wire tails to create a complete circuit. If assembled correctly, this battery should power a small LED bulb.