A light circuit is simple, but effective. Solder a couple of wires onto the two terminals on a flashlight. Wire in a small on/off switch. Connect the end of one of the wires from the light bulb to a terminal on the switch and then connect the end of a third wire to the other terminal in the switch. Solder the end of the wire from the switch and the other end of the wire from the light bulb to the two terminals on the battery. Turn on the switch and the light illuminates.
Wrap wire tightly around a 3-inch nail. Start at the top and wind the wire to the bottom of the nail then, up and down again. Leave a few inches of wire loose at the top and bottom of the nail to solder the wires to a battery. Use a strip of adhesive tape and strap an AA battery onto the wire around the nail. Solder the loose wire from the top of the nail onto the top battery terminal, then solder the wire from the bottom of the nail to the bottom battery terminal. Move the nail toward a metal item; it sticks to the metal item.
Wrap wire neatly, but tightly around a 2-inch by 3-inch piece of thick card. Leave several inches of wire loose at the top, but none at the bottom. Solder a wire onto a terminal on a light bulb. Solder another wire to the other terminal on the light bulb. Attach a paper clip to the opposite end of one of the wires from the light bulb. Solder the opposite of the other wire to a battery terminal. Solder the loose wire from the top of the card onto the other battery terminal. Move the paper clip along the wire wound around the card. The nearer the paper clip gets to the top of the card, the brighter the light gets.
Make a rheostat the same in the previous section. However, instead of wiring in a light bulb, wire in a small electric motor. The wiring is the same as before. Get your paper clip and put it at the bottom of the card farthest away from the wire at the top that goes to the battery. Watch your electric motor rotate very slowly. Gradually move the paper clip up toward the top of the wire winging on the card. As you move the clip up, the motor starts to spin faster. When you get to the top, the motor is running its fastest.