How strong is an eggshell?

This egg experiment looks at how something we think of as being brittle and weak can actually hold a heavy load under certain conditions. We're going to investigate how strong an eggshell is by using half shells to make a bridge.

How strong is an eggshell?

You'll need

• at least four eggs ( we broke a few making the domes )
• a pen
• scissors or a sharp knife
• heavy books

How to make an eggshell bridge

• Tap the end of an egg gently on a hard surface to break it. Empty out the contents ( maybe use it to make scrambled eggs? ) and rinse the inside of the shell. You'll need four eggshells (so probably more than four eggs, as the domes can be tricky to make).  Take a moment to think how brittle and easy to break the eggshell is.

Method 1

• Draw a line around the egg as evenly as possible, then using the line as a guide, carefully score the shell. Ask an adult to do this.  It is worth spending a lot of time on this step, as we have found it frustratingly difficult.  Ensure the scoring is continuous and completely encircles the egg.

Method 2 - the easiest

• Very carefully break off pieces of shell up to around the centre point.  You need four half eggshells of the same height.  Scissors sometimes work, too.

• Place the four shells in a rectangle shape, and slowly place books on top. See how many books you can add before the eggshells crack.

Image taken from Snackable Science

How strong is an eggshell?

Some shapes are stronger than others.  Eggs which seem fragile are actually very strong in certain ways (try crushing an egg by squeezing the ends between your hands (maybe over a sink or outside!).

Eggshells naturally form a dome shape.  Domes are very good at spreading weight evenly in all directions so that no part of the dome has to support more weight than another part.  The downward force of the weight of the books is transferred evenly by the dome shape down to the hard surface

Think more: What other shapes are strong? Where can you see these shapes in buildings or nature?

Starter: Have a look at bridges.

Try our investigation using paper to find out about strong shapes.

More Science for Kids

Make an unbreakable egg or try one of my other easy egg experiments for kids, including making a naked egg, a bouncy egg and a Humpty Dumpty egg drop.

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Last Updated on February 29, 2024 by Emma Vanstone