Demonstrate the strength of a suspension bridge using eggshells

	Project title: Demonstrate the strength of a suspension bridge using eggshells
Difficulty level:	Elementary school
Main link:	None

Hypothesis:

Why igloos are dome shaped and not square?

Materials:

four eggs
tape
books

The Procedure:

break off the small end of four eggs
wind a piece of cellophane tape around the center of each eggshell
cut through the center of the tape to make four dome-shaped shells
lay the four domes on a table with the cut sides down arranged in the shape of a rectangle
guess how many telephone books can lay on top of the shells before they break

Results:

ARches are strong because they exert horizontal as well as vertical forces to resist the pressure of heavy loads.
The crown of an eggshell can support heavy books because the weight is distributed evenly along the structure of the egg.