Step 5: Floating eggs!
First fill one of your containers with plain water and put an egg in it. What happened?
The reason it sunk was because water is not dense enough to hold the egg up (keep it floating).
Now make salt water by adding about 4 tablespoons of salt in about 2 cups of water. Put this salt water in your other container. Then put the egg in that container... The reason it floats this time is because the water is dense and therefore it can keep the egg on the surface.
Now to get the egg to float in the middle fill a container half way with salt water. Now pour regular water down the sides of the glass to ensure the liquids don't mix. Once the liquids are in the container drop the egg in. Notice how it drops through the water and then stops when it reaches the salt water. This is due to the different densities I discussed earlier.