Most of the information below was found at   http://www.eggsedu.org.uk            
The Inside Story  

All baby birds hatch out of eggs.
The mother bird lays the eggs.
The chick grows inside the egg.
The egg must be kept warm.  (About 100 degrees F.)
After 3 weeks the chick hatches.  (Our chicks took longer!!)

Hens must mate with a cockerel to make a chick.
Chicks do not grow inside the eggs we eat because
they have been laid by hens which have not mated.

Nearly all animals produce eggs, but only some of them lay eggs
outside of the body. The shell of a bird's egg is one of nature's great
design solutions: thin, porous, yet amazingly strong.
Eggs are shaped and structured to provide protection and nutrients for the developing embryo.

The structure of a chicken's egg.

Birds' eggs have 5 important parts. The most important is the germinal disk.
This is found inside the yolk and is the cell nucleus from which the young bird
would have developed if the egg had been fertilized.
Commercially produced eggs for eating are never fertilized.

The bulk of an egg consists of a thin white solution of proteins, mineral elements,
carbohydrate and water called albumen. In chickens' eggs this makes up 58%
of the total egg mass. Egg yolk makes up the remaining 31% and is held in place by
two dense cord-like strands which are called chalazae.

The shell of an egg is made from a type of calcium carbonate called calcite.
This is the same material that also occurs in marble, limestone, coral and chalk!
Eggs shells vary naturally in color, depending on the breed of the hen.

Inside this thin shell are two semi-permeable membranes. These act as filters to
protect the egg's contents from dirt and bacteria. The outer membrane is
the one upon which the shell is built. The inner membrane surrounds the
white and the yolk. A third membrane, the vitelline membrane, supports the yolk.