Turn Easter egg decorating into an experiment and find out how wax affects the egg-dying process. Decorate a white hard-boiled egg using white wax crayons. Draw polka dots, stripes, flowers or your name on the egg. Then dip the egg into a vinegar-based dye. When you remove the egg, you will notice that the crayon marks remain white while the rest of the egg has turned the color of the dye. This happens because the wax prevents the dye from bonding with the eggshell.
For this experiment you will need one hard-boiled egg and one raw egg, approximately the same temperature. To find out which egg is raw and which is cooked without cracking them open, spin them on a flat surface like a toy top. Observe how each egg spins. The raw egg will wobble as it spins while the hard-boiled egg will not. Explain that the raw eggs wobble because of the liquid moving inside them, and that the hard-boiled eggs don’t wobble because they are solid.
Examine the inside of an egg without cracking it open and observe the effect vinegar has on an eggshell. Complete submerge a raw egg in a jar of white vinegar. Put the jar in a refrigerator and leave it there for two days, changing the vinegar in the jar after 24 hours. Pour the vinegar off. Only a thin, transparent membrane now holds the egg together; the shell has disappeared. This happens because the vinegar dissolves the eggshell, allowing you to see the egg yolk through the membrane.
To make eggs float, fill two containers with warm water. Dissolve two or three large spoonfuls of salt in one of the containers. Gently place one raw egg in each container. The egg in the unsalted water sinks to the bottom while the one in saltwater floats. The salt makes the water denser or heavier than plain water. In fact it becomes more dense than the egg which is why the egg floats. Since the unsalted water is not as dense, the egg has the greater density and falls to the bottom of the container.