The Uncanny Unbreakable Egg

Try crushing an egg with your bare hand, applying even pressure all the way around. Not so easy, is it? (note: do not try this with rings on your fingers.) Eggs are naturally resistant to crushing (or compression) because of their dome shape. This curved shape spreads the pressure placed on the egg around the entire shell, allowing it to support more weight. The same principle is used on bridges, arches and other weight-bearing structures.

How it looks:

Bet a friend that you can balance a pile of books on egg shells without crushing them. Place four egg shell halves on the table rounded side up, so they support the four corners of the books. Carefully balance the books one by one on top of the shells and see how many books you can pile before they crack.

What you need:

• 2 eggs
• Small container with lid (only if saving egg for future use)
• Water (to wash the egg shells)
• Paper towel (to dry the egg shells)
• Scissors
• Masking tape
• 4 or 5 hard cover books (all about the same size)
• Adult helper

How it works:

Carefully break the two eggs in half. Save the yolk and whites for cooking/baking or throw out. If saving, put them in the small bowl with a lid and then in the refrigerator for later use. Carefully wash and dry the egg shells. Wrap masking tape around the broken edge of each shell. Cut the taped edges of the shells so that they sit flat. Try to make these all roughly the same height so the weight of the books is distributed evenly across the four shells.

Did you know…

A hen’s diet will greatly affect the strength of an egg shell. Calcium, phosphorus, manganese and Vitamin D are important minerals and vitamins for healthy shells. If the diet is deficient in calcium, for instance, the hen will produce a thin-shelled egg.

Sources: Adapted from and