Like a scientist, we will do an experiment to see if there are tiny holes in eggshells. Each person or pair needs to fill their jar half full with warm water. Place one egg into the glass jar. Carefully observe or watch what happens to the egg. There is air inside the egg that can get outside.
Air can escape from the inside because there are very tiny holes in the eggshell.
This means the eggshell is porous, or it has little holes in it, so that air or water can go in or out of the egg. If there were a baby bird growing in our egg, it would need air. This is how air would get into the egg. Give each person or pair an aluminum pie pan. Demonstrate how to crack open an egg and put the contents inside of it onto the pie pan.