SOURCES OF FOOD
All nature supplies us with food. The three great divisions of nature are animal, vegetable, and mineral, and from each we obtain food, though most largely from the animal and vegetable kingdoms.
Animal food is some part of an animal's body or some product of an animal: examples—meat or fish, milk, eggs.
Vegetable food is some part of a plant: examples—vegetables, fruit, seeds.
Mineral food is some constituent of the earth's crust used as food. This mineral food is obtained by drinking water which in coursing through the earth has absorbed certain minerals, by eating plants which have absorbed the minerals from the soil, or by eating animal food which was built from plant food.
This preliminary survey of the sources of all our food gives the pupils a basis for classifying the foods with which they are familiar. They may be given exercises in doing this, and will not only find them interesting, but most useful as nature study.
STUDY OF THE COMMON FOODS
In beginning the analysis of the common foods, it must be remembered that the pupils have no knowledge of chemistry, and that what is found in each food must be discovered through the senses (seeing, smelling, tasting, feeling), or through a process of reasoning.
The pupils should also feel quite sure of what they are setting out to do; they are going to examine some particular, well-known food, to find which of the necessary food substances it contains. The food substances for which they are looking are water, mineral matter, nitrogenous matter, and carbonaceous matter (sugar, starch, fat).