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Why Mama Bird Doesn't Squash Her Eggs


Today's Snack: Use the insides of the eggs from this project for a big omelet!





Six large eggs | scissors | bowl to keep egg yolks and whites

Serrated knife | toothpick | section of paper toweling

Three to four dictionaries or other thick, heavy books | masking tape


Have you ever wondered how a mother bird could sit on the eggs in her nest and not crack them open before the babies even hatch?


The reason she doesn't have to worry is that eggs are designed to be very, very strong. The shape of an egg - a dome or an arc - distributes weight all over the surface, so that there really isn't a weak point that will give way very easily.


If you have an extra egg besides the six for this activity, hold it in your hand. Try to crush it. Can't do it, eh? You have to tap an egg against a hard surface to get it to crack.


Do you think if you piled several heavy books on top of some eggshells, they'd crack? Oh, yeah? Well, let's try it.


1.      First, make a "hypothesis" - pronounced "hi POTH uh siss" -- an educated guess - on whether these shells will break after one, two or three heavy books are piled on them. See if you're right!


2.      Now empty out the contents of the six eggs into a bowl so that you can make an omelet. All you want is the shell. You going to break it open on just one end.


3.      Using a serrated knife - pronounced "SARE ate ed" -- one with sharp little points all along the edge -- carefully cut about a dime-size hole off one end of each egg. Shake the yolk and the egg white into a bowl and set it aside. You may have to stick a toothpick in there to break the yolk to get it out.


4.      Wash the shells with warm, soapy water and let them dry. Wash your hands after handling eggs, too!


5.      Once the eggs are completely dry, apply a small piece of masking tape over the hole to cover it. That will be the bottom of the egg. It should sit pretty still. Try to have your six eggs rest as flat to the surface of the table or desk as you can.


6.      Arrange the eggshells in a square - three rows of 2 - on a piece of paper toweling. Put one dictionary on top. Does it break the eggs? Continue with a second and third big book. Keep going until and unless your eggshells break.


7.      Was your hypothesis right?


8.      Did you observe anything interesting during this experiment?


9.      What is your conclusion?


10. Why do you think eggs are shaped this way, in nature?


11. Can you think of applications for this knowledge in the real world?


12. Did you have fun? That's eggs-actly the point!



By Susan Darst Williams www.AfterSchoolTreats.com Experiments 08 2010***

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