Take a raw egg and put it in a glass. Cover the egg with vinegar. Look at it a couple hours later and you will see bubbles all over the outside of the egg. This is a chemical reaction. The vinegar combines with the molecules of the egg shell to form a gas: carbon dioxide (CO2).

Change the vinegar twice a day. In a couple days the eggshell will be completely gone. What you have now is one giant cell! While most cells are microscopic, an egg is a type of cell that you can see without a microscope. Handle the egg gently and throw it away in a day as it will start to smell.

Harriet Vender is a 7th and 8th grade science teacher