How Strong Are Eggshells?

Everyone knows that eggshells are fragile ... or are they? If they are so fragile, then how can a bird sit on eggs and not end up with a nest full of scrambled egg?

How Strong Are Eggshells?

Recently, we experimented with eggs to find out how strong are eggshells. We were amazed to discover that eggshells are not as fragile as we first thought!

Carefully cut the eggshell in half

We started with two eggs and enlisted the help of Dad to carefully cut them in half width-wise. (Hooray for Dad's ... or Mum's ... with tools!)

Note: If you don't have anyone standing by with the appropriate tools to cut an egg in half, apparently you can also do this by sticking masking tape around the middle of the egg and then cutting the egg with scissors.

It's important to ensure the cuts are as smooth as possible and any jagged edges are removed.

Sandwich the eggshells between two layers of cardboard

Next we sandwiched the eggshell halves between two pieces of cardboard. The cardboard helps to spread the weight evenly over the four halves equally.

Stack the blocks carefully on top of the cardboard

It was time to start gently stacking blocks on top, taking care to spread the weight evenly over all the eggshells.

No cracks yet!

We kept checking the eggshells, fully expecting to see cracks appearing in our eggshell foundations.

Build the tower higher

Watching our tower grow while waiting for the foundations to crumble was oddly fascinating and thrilling. (Okay, I admit it ... I loved this experiment!!! It was so much fun!)

Higher and higher

It wasn't until after the twelfth layer of blocks had been added to the tower that we heard the first creaking crack appear in one of the eggshels.

I heard a crack!

The eggshell to finally give way was the one that had a small chip in its edge to start with.

The eggshells held up 5 kgs of weight before one cracked

So what was the answer to our question, 'how strong are eggshells?'. It turns out that the eggshell halves held a whopping 5 kilograms before finally cracking! That's a lot of weight for two eggs ... or four eggshell halves. We concluded that eggshells are very strong and can support a tremendous amount of compression weight!

The eggshell with an uneven base-edge was the one to give way first

The Secret of the Egg

The strength of the egg lays in its shape ... a dome. When weight is placed on the eggshell, no single point of the eggshell dome supports the weight solely. Rather, the weight is spread along the curved walls of the dome to the wide base. This allows the eggshell to support more weight which is compressed onto the eggshell.

An eggshell will break, however, when force is applied to a single point of the eggshell which is what happens when a chick pecks at the shell in order to hatch.

Having had so much fun with this egg experiment, we tried another how-strong-are-eggshells-experiment ... The Unbreakable Egg.

We've also started checking out buildings which incorporate domes. It turns out that dome buildings are incredibly strong ... much stronger than a traditional home with four walls and a roof. Maybe our next house should be an igloo? :o

By the way, if you're looking for a humourous story full of eggs, then check out Farmer Blake and Sneaky Snake.

Apps By Stories And Children
You may also like these activities:

The Unbreakable Egg
The Unbreakable Egg
Farmer Blake and Sneaky Snake: A story full of eggs!
Farmer Blake and Sneaky Snake: A story full of eggs!

Return to the Articles List for other children's learning activities or children's book reviews.

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