The incredible egg is more than just edible. It is the first appearance of nearly every earthly animal, and as such deserves a second look. Children, with a curiosity unnarrowed by specialization, make some of the best lookers.
Although animals from alligators to zebras produce eggs, chicken eggs are easiest to obtain. The children will enjoy comparing the chicken's effort to that of robins and turkeys, if this can be arranged.
Let your children feel a chicken's egg, and describe its shape, color, and size to you. Then, crack it carefully and slip the insides onto a plate.
The children should be able to point to the yolk in its sac, and the albumen (egg white) around it, but you need careful eyes to see the chicken. A small white spot on the yolk is the start of the baby chick; once this is fertilized inside the hen, it starts to grow and divide. The spot has a name befitting a "Star Wars" weapon your children should enjoy: It's called a blastodisc.m
The yolk contains food for the growing chick, and acts as a pillow for the embryo. A thin film, or sac, keeps it separate from the egg white. Your children can feel the strength of this sac by prodding it gently; breaking it is fun, too.
Your children can also feel the liquid albumen, whose chief job is to keep the egg moist. The first animals on earth laid their eggs in water, so moisture was no problem. As animals crawled onto the land, however, keeping the eggs wet and at an even temperature became difficult.
By enclosing the egg in a hard shell and providing the moisture of the albumen and the warmth of the mother's body, nature solved these challenges. More details on how the chicken grows inside the shell can be found in Millicent Selsam's simple book, "Egg to Chick."
Show children how to separate the yolk from the white. They can do this easily by pouring the egg through their fingers, being careful not to break the delicate yolk. This done, you can demonstrate the usefulness of eggs in cooking.
For as long as animals have produced eggs, they have eaten them -- a fact that gives new dimension to the term "protecting the young." Eggs lend themselves to a wide variety of dishes and cuisines; you probably have your own favorites.
The egg yolk is a particularly good binder, a role easy to see in the making of custard. Milk heated with sugar is sweet milk; heated with an egg yolk or two, it takes on a different consistency.
Changes in consistency are more dramatic with the albumen. Ask your children why you call it an egg white -- not because of its color, surely. Then slip the whites into a deep bowl with straight sides and start beating them.
When the mixture becomes frothy, add a dash of cream of tartar; this aids in the stiffening process. Let the children help beat it until the whites form peaks. Then ask them why you call it "egg whites."
If you add a cream sauce with cheese or cooked vegetables, you have the makings of a souffle (check your favorite cookbook for the exact proportions). This will continue to grow a bit in a hot oven; let your children watch through the oven window, but do not open the door until the souff le is finished cooking.