Science Experiments for Kids: Make a Lemon Clock

Conduct Your Experiment

Create a Hypothesis

1. Go over the background information about electricity and batteries here with your child to make sure she has a basic understanding of how batteries and conduction work. Show your child the materials you have, and tell her that you are going use them to make the clock work without a battery.
2. Identify each of the materials by name and composition (i.e., a copper nail, a zinc nail), and ask her to predict what will happen if you connect all these materials together.
3. Have her make a basic diagram of what she thinks you need to do and what will happen. This will serve as her plan and hypothesis.

How to Play

1. Securely attach one end of a piece of copper wire just below the head of one of the zinc nails by wrapping it around the nail. Attach a small alligator clip to the other end of the wire. If you do not have alligator clips, leave the end of the wire as it is.
2. Attach the end of a second piece of copper wire to a copper nail by twisting it around the nail (or, if you are using a penny, attach it with electrical tape). Attach the other alligator clip to the other end of this wire. Again, if you do not have alligator clips, leave the end of this wire as it is.
3. Secure a zinc nail to one end of the third piece of wire and a copper nail (or penny) to the other end of it.
4. Set aside the wiring for a moment, and prepare the lemons. Use a permanent marker to label one lemon as Lemon 1 and the other as Lemon 2. Next you need to loosen the pulp inside and release some of the juice into the lemons without breaking the peels by squeezing the lemons gently, and/or rolling them on a table while applying gentle pressure.
5. Place Lemon 1 and Lemon 2 next to each other on a table. Locate the wire attached to the first zinc nail, and poke the nail into Lemon 1, making sure the nail pierces the peel and is embedded in the pulpy portion of the lemon but does not come out the other side of the lemon.
6. Locate the wire attached to the copper nail or penny. Drive that nail into Lemon 2 (or cut a deep slit in the lemon, and place the penny in the slit).
7. Next, take the wire with a copper nail on one end and the zinc nail on the other end. Drive the zinc nail into Lemon 2, approximately an inch away from the copper nail or penny already embedded in the lemon.
8. Insert the copper nail/penny end of the same wire into Lemon 1, about an inch away from the already embedded zinc nail. 9. Connect the free end of the wire in Lemon 1 to the clock by clipping the alligator clip onto one of the battery terminals in the clock. If you do not have alligator clips, attach the end of the wire to the terminal with electrical tape. Complete the circuit by attaching the free end of the wire in Lemon 2 to the other battery terminal in the same way. Completing the circuit should power the clock. If the clock isn't running, it may be that the connections are loose, the ends of the wires connected to the clock are attached to the same metals, or that the current from the lemon is just too weak. If all the connections are right, try substituting potatoes for lemons.