Foam cakes are cakes with very little fatty material such as butter, oil or shortening. They are leavened primarily by the air that is beaten into the egg whites that they contain. The leavening agent (mechanical) comes from the egg whites and the air that is mixed into them.
You can see how fluffy the foam cake is from the egg whites as the leavening agent.
Whisk dry ingredients together thoroughly.
Whip eggs/yolks/whites (depending on your recipe) with sugar until very light in color, tripled in volume and creamy. ...
Pour egg mixture into a large bowl.
Sift dry ingredients over the egg mixture and gently but thoroughly fold together
This recipe shows how we were able to demonstrate the foam cake method with the mechanical leavening and the folding in of the ingredients
This video represents exactly how we made the angel food cakes in class