Are Egg Shells Weak or Strong?

The children at school wanted to spend some time celebrating Easter.  We went on an Easter Egg Hunt, decorated eggs, and did some science! 

I asked the children if they thought that egg shells were weak or strong.  Most of the children said "weak" because "Humpty Dumpty sat on a wall... Humpty Dumpty had a great fall!"  I asked them what would happen if I squished an egg shell in my hand or jumped on it with my feet.  They responded, "It would break!"

Then I asked, "Do you think the eggs are strong enough to hold up these blocks?"  Some said, "Yes", others "No" and some "Maybe".  We made predictions on how many blue and red cardboard boxes we could stack on the shells before they broke.  I set 3 half egg shells up in a triangle shape.

We stacked 10 of the cardboard boxes on and that was more then all of our predictions!

Then we tried the heavier wooden blocks.  The children determined that these heavier blocks would break the eggs.  Their predictions were correct! 

We learned that eggs are stronger then we thought.  When we put the blocks on gently they didn't break but if we were rough and dropped the block on the egg shattered.  The same thing happens when we drop one on the ground!  Humpty Dumpty!