t 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).

It is better to provide each pupil with a sample of the food to be
studied, but where conditions make this difficult, the one used by the
teacher will suffice.

STUDY OF MILK

LESSON I

COMPOSITION

Milk is the best food to examine first, because it contains all the food
elements except starch and because these can be easily found.

The pupils may each be asked to bring a half cup of milk from home. It
may be allowed to stand in glasses while other work is taken.

When ready for the lesson, ask the pupils to look at the contents of the
glass, and they will observe a difference of colour where the cream has
risen. Nature itself has divided the milk into two parts. Pour off the
top part and feel it. It feels greasy. Butter is made from this part. We
have found _fat_--a carbonaceous food.

Move the milk around in the glass and let the pupils see that it is a
liquid. Tell them that all liquid in a natural food is mostly water. We
have, therefore, another food substance--_water_, a builder and
regulator.

Let the pupils compare a glass of water with a glass of skimmed milk,
and they see that something is dissolved in the water of the milk,
giving it the white colour. Show them a glass of sour milk, where the
white substance is separate from the water. Get the names curd and whey.
Tell them how the cheesemaker separates sweet milk into curd and whey.
If advisable, let them do it, but in any case show them some sweet milk
separated by rennet. Examine the sweet whey. It tastes sweet, denoting
the presence of _sugar_--another carbon