Teach kids about osmosis by experimenting with eggs and vinegar. Have the kids place a raw egg, in the shell, in a bowl of vinegar so the egg is completely covered. Wait two days, then carefully drain the vinegar from the bowl. Gently lift the egg, being careful not to break the membrane. The kids will notice that the egg feels rubbery. Discuss that the vinegar is acidic and absorbs into the eggshell, dissolving it. What is left is a flexible membrane that holds the egg together.
Kids can learn about the effect that the gravitational pull of the sun has on balance. On the spring or autumn equinox (about March 20 and Sept. 23), give kids a raw egg and ask them to try to balance it on end on a clean table. It is said the gravitational pull of the sun can help the egg stand on end. Next, have the kids create a small mound of salt on the table, and balance the egg on the salt. Once the egg is standing upright, carefully blow away the excess salt. The salt crystals are tiny cubes that create a pedestal for the egg to rest on.
Teach kids about density with a floating/sinking egg experiment. Fill two bowls with warm water. Add three tablespoons of salt to one bowl of water and stir until the salt is completely dissolved. Label the bowels so the kids don’t mix them up. Next ask the kids to put one raw egg in each bowl. The egg in saltwater floats and the other sinks because saltwater is denser than plain tap water.
Use the bottled egg experiment to teach kids about air pressure. Find a glass bottle with an opening a bit smaller than an egg. Have kids place the bottle in a bowl of warm water for about five minutes, then move it to the bowl of ice water. Place a wet, peeled, hard-boiled egg in the opening of the bottle with the narrow point facing down. The egg will slowly slide into the bottle. Have the kids remove the egg by holding the bottle upside down so the egg is near the opening. Next, ask one kid to blow hard into the bottle with his mouth tight around the opening. The kid should then turn the bottle away from himself and the egg will fly out! Hot air expands and cold air contracts, causing the egg to be pushed into the warm bottle. Blowing in the bottle raises the air pressure causing the air and egg to rush out.