The purpose of this experiment is to see the effects of acid (vinegar) on bones and other hard materials. Bones that contain calcium often react in interesting ways to being soaked in vinegar or another type of acid. This experiment can demonstrate why it is important to get enough calcium and what happens when a bone or skeleton loses significant amounts of calcium.
Save some chicken bones and boil them to remove as much of the meat as you can. Note how the chicken bones look and feel. Place the chicken bones in a glass and pour household white vinegar into the glass. Add enough vinegar to cover the bones completely. Leave the bones at room temperature for a few days, adding more vinegar if needed to keep the bones completely covered. After two or three days drain the vinegar and rinse the bones.
Examine the bones once you have rinsed them off. Note how the chicken bones look and feel after being soaked in vinegar. Try bending or breaking one of the bones. Think about what the acid in the vinegar did to the calcium in the chicken bones. How does this relate to what goes on inside the body and what does it mean? What else might change the results of this experiment?
As a variation on this experiment, try using different types of bones and other materials. Observe what happens when you use crab shells, beef bones, fish bones, eggshells, a tooth or even fingernail clippings. You can also try and vary the soaking liquid. With close adult supervision children can observe the results of soaking things in rubbing alcohol, ammonia-based cleaning solutions, bleach or plain water and compare them to the results of soaking materials in vinegar.