d? It was
removed by scraping or rubbing.

Suppose some one has sharpened a pencil and let the pieces fall on the
floor, what would you take to remove the foreign substance from the
floor? A broom. What would you say you are doing with the broom?
Sweeping. How does the movement of the broom over the floor compare with
the movement of the knife over the plate? It is similar. What would you
take to remove the dust from the window-sill? A duster. What would you
say you are doing? Dusting. How does the movement of the duster compare
with the movement of the knife and the broom? It is similar. In all of
these cases of dish, floor, and sill, how did we remove the foreign
substance? We scraped or rubbed it off. Name one way of removing a
foreign substance. Scraping or rubbing it away.

2. _Dissolving the foreign substance and then scraping it away:_

Show a much soiled towel and ask what is usually done to clean it. It is
washed. Ask the pupils to tell just what they mean by that. The towel is
put in water and soap used on it. What effect will the soap and water
have on the foreign substance? They will soften or dissolve it. Then
what must be done next? The towel must be rubbed on a board or with the
hands. What effect has this operation on the foreign substance? It
scrapes or rubs the foreign substance away. Then we have another way of
cleaning: By first dissolving the foreign substance, and then scraping
or rubbing it away.

A number of well-known cleaning operations may then be given, and the
pupils asked in each case to decide the method used--such as, whisking a
coat, scrubbing a table, cleaning the teeth, or washing dishes.

COMMON HOUSEHOLD CLEANSING AGENTS

Next, get lists of the common cleansing agents found in an ordinary
home, and arrange them in order of coarseness.

BLACK-BOARD OUTLINE

The black-board scheme, as the lesson develops, will appear as follows:

1. _Meaning of Cleaning:_

Cleaning is removing any foreign substance.

2. _Methods of Cleaning:_

(1) Scraping or rubbing away the foreign
substance.

(2) Dissolving the foreign substance and then
scraping or rubbing it away.

3. _Household cleansing agents used in the first method:_

(1) Duster
(2) Brush
(3) Broom
(4) Washboard
(5) Knife
(6) Whiting
(7) Bathbrick
(8) Coarse salt
(9) Sand
(10) Ashes.