CHAPTER V
FORM III: SENIOR GRADE (Continued)
COOKERY
LESSON I
After a number of practice lessons have developed in the pupils a certain ability and self-confidence in working, formal cookery may be introduced, and the following ideas should be brought out:
1. The meaning of cooking:
Cooking is the application of sufficient heat to make a change in the food.
2. Reasons for cooking food:
(1) To make some food digestible.
(2) To change flavours and make some food more appetizing.
(3) To preserve food.
(4) To kill harmful germs in food.
3. Kinds of heat used:
(1) Dry heat--heat, only, is conveyed to the food.
(2) Moist heat--heat and moisture are conveyed to the food.
4. Different ways of applying _dry heat_:
Toasting, broiling, pan-broiling, sauteing, frying, baking.
5. Different ways of applying _moist heat_:
Boiling, simmering, steaming, steeping.
NOTE.--If the class cannot name these methods, the teacher may name and write them with only a word of comment regarding each, or they may not be given until the methods are studied.
As the moist heat methods are simpler and better known, they should be studied first. The class should be led to see that some liquid must be used to supply the moisture and should account for the common use of water for this purpose. Experiments should then be performed in heating water, and its appearance and temperature should be noted.
NOTE.--A preliminary lesson on the use of the thermometer may be necessary to show how to read it, and to develop the idea that it is an instrument for measuring heat. This may be taught in the regular class work, previous to the Household Management lesson.
LESSON ON THE THERMOMETER
1. Development of the idea of "measuring":
What would you use to measure the length of the table? A foot measure.
What to measure the water in a tub? A pint, quart, or gallon measure.
What to measure the amount of gas burned? A gas-meter.
2. Development of the name "thermometer":
What do we call the instrument
For measuring gas? A gas-meter
For measuring electricity? An electrometer
For measuring speed of a motor? A speedometer (speed-meter)
For measuring the distance a bicycle travels? A cyclometer (cycle-meter).
In each case what does "meter" mean? It means an instrument for measuring. What name may I give to an instrument for measuring heat? You may call it a heat-meter.
Tell the pupils that, in science, many Greek words are used, and that you will put a Greek word in place of the English word "heat", namely "thermos", as in thermos bottle. What will the name become?
Thermosmeter, or _thermometer_.
3. Practice in using thermometers:
The unit of measurement (_degree_) should be given, and the scale taught from the black-board. Thermometers may then be given to the class to examine and use.
Saucepans having white inner surfaces are best to use for the experiments, as changes made by the heat are more plainly seen.
_Observations of water under heat:_
(1) At a temperature of about 100 degrees, very small bubbles form at the bottom and sides of the dish and rise slowly to the surface of the water. These bubbles are a film of water containing the air that was in solution, which, when expanded, rises to the top of the water.
(2) At a temperature of about 180 degrees, a few larger bubbles form at the bottom of the dish and rise slowly to the surface of the water, making a slight movement in it. In these bubbles air is replaced by steam which is formed from the water by the heat.
(3) At a temperature of 212 degrees, a great number of large bubbles form and rise quickly to the surface, making much movement in the water. The water is then said to boil.
(4) The water will take no higher temperature than 212 degrees.
(5) After water once boils, it requires little heat to keep it at this point, therefore the heat may be reduced.
(6) An increase of heat increases the number, size, and rate of the bubbles and the volume of steam, but makes the liquid no hotter.
_Application of these observations:_
(1) If food be cooked in a liquid at its greatest heat, where many bubbles are making much movement in it, the process is called _boiling_.
(2) If cooked in a liquid heated to 180-200, where there is scarcely any movement in the liquid, the process is called _simmering_.
(3) If cooked in the steam rising from a boiling liquid, the process is called _steaming_.
(4) If boiling liquid be poured over food and no further heat applied, the process is called _steeping_.