The Incredible Egg – Raw or Hard-boiled?

Science
Time 15 minutes
Age 5 & up
Group Size 4 or more
Tags Cooking, Egg

Hungry for a hardboiled egg?

Spring is a time of rebirth and renewal—and eggs! Many animals lay and incubate eggs in the spring, and in some cultures spring is a time in which kids paint, hide and eat lots of eggs. This makes it a great time to not only take a close look at eggs, but also to experiment with some of the things we can do with them. This activity is part of the Incredible Egg series of activities, which are designed to be done during the Spring—start your students off with this and other “egg science” activities, then move on to egg art, and finally take the Egg Drop Challenge!

Preparation

See the instructions for The Incredible Egg for preparations regarding all of the activities in this series. For this activity, gather the raw eggs and the hard-boiled egg that you have prepared. Make sure to try out all of the other “Incredible Egg” activities:

Egg Science Activities

The Incredible Egg (aka “How Strong is an Eggshell?”)
The Emperor’s New Egg
Raw or Hard-boiled?
Fresh or Old?

Egg Art Activities

Egg Painting
Eggshell Mosaics
Egg Dyeing with Natural Dyes

Culminating Activity

Egg Drop Challenge

The Incredible Egg – Raw or Hard-boiled?
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Suggested Materials

  • 5 raw eggs
  • 1 hard-boiled egg (cold, with no cracks in the shell)
1

Make it Matter

Opening Discussion

Ask your students how many of them eat eggs. Have they ever had a hard-boiled egg before? Can they tell if an egg is hard-boiled just by looking at it? Can anyone think of a way that they might be able to tell the difference between raw and hard-boiled eggs without cracking them open?

The Challenge

Figure our which is which without having to open the eggs up!

2

Make it Happen

Doing the Activity

  1. Place the eggs on the table and tell your students that you have come across a problem – you want to eat a hard-boiled egg, and you know that you have one of them…but it got mixed up with some raw eggs. You don’t want to open the eggs up, because that would waste any raw eggs that you broke open. How can you figure it out without breaking any eggs?
  2. Let your students think and try a few things out.
3

Make it Click

Let’s Talk About It

After a few minutes, ask your children to talk about their theories of how you can determine which eggs are which.

4

Make it Better

Build On What They Talked About

If no one comes up with this method, show them this: Take 1 egg and spin it on its side (not on its pointy end). Stop the egg by briefly (and gently!) touching it with your finger just long enough to stop the spin (it should just be a split second), then lift your finger up off of the egg. Some eggs will stop spinning after you lift your finger up, while others will continue to spin. Does anyone have any guesses as to which egg is which?

After they talk about their ideas, you can tell your students that the hard-boiled egg is the one that stopped spinning, and the raw eggs are the ones that continue to spin after you lift your finger up. To prove it to them, take the hard-boiled egg (the one that stopped spinning) and crack it against the table. Unpeel the egg and enjoy.

Suggestions

  • Because the raw eggs are liquid inside, and your finger only touched the shell, the liquid inside will continue to slosh and spin, which will cause the whole egg to spin even after you stopped it. The hard-boiled eggs have been cooked until solid, so the shell and inside spin as one, and also stop together.
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