Ask your parent to hard boil an egg for you. Get them to give
you a hard-boiled egg and a raw egg. Make sure they mix them up so
you don't know which one is which.
How can you tell the difference between the two eggs,
without breaking them?
Try it out and see! Be careful the raw egg doesn't end up like
this:
Here's how you tell the difference between a hard-boiled egg and
a raw egg:
Spin both the eggs and see what you notice.
The raw egg will spin more slowly and it will
wobble! This is because the raw egg is fluid
inside, whereas the hard-boiled egg is solid. When you spin the raw
egg, the fluid inside moves around and causes the wobbling. The
hard-boiled egg has no fluid, so it doesn't wobble.
Put your finger briefly on the eggs to stop them spinning. When
you take your finger away, the raw egg will continue to spin for a
few more seconds, as the fluid inside is still moving. The
hard-boiled egg will stop instantly.
Try it on your friends and family and see if they can tell the
difference.