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18 BULLETIN 440, U. S. DEPARTMENT OF AGRICULTURE. 
LESSON 27. 
General review. 
LESSON 28. 
Problem.—To finish apron and cap. 
Supplementary topics —How might six neighbors organize a maga- 
zine club, each subscribing for one magazine and exchanging, so as 
each to get the use of allsix? Draw up plan, list of magazines, costs, 
rules for ordering, for exchange, etc. 
LESSON 29. 
Problem.—To sterilize petri dishes and plate. Pour tubes of agar 
into petri dishes for experiments in the next lesson. 
Notre.—The tubes of agar should be prepared by the teacher or an advanced class. 
Points to be brought out.—For any material to remain aseptically 
clean it must not be touched by anything which has not been sterilized. 
Reference.—Any good bacteriology of the household. 
LESSON 30. 
Problem.—The weekly care of the bedroom. On the day usually 
devoted to this work the room should be carefully cleaned and an 
account written of the various steps, with the reasons for them. The 
following experiments with the petri dishes are suggested to make 
the reasons for the various steps in the cleaning process more clear: 
Expose 12 petri dishes as follows: (1) Immediately after sweeping 
a carpet, (2) immediately after sweeping a bare floor, (3) one-half 
hour after sweeping, (4) one hour after sweeping, (5) one and one- 
half hours after sweeping, (6) two hours after sweeping, (7) after 
dusting with a feather duster, (8) after dusting with a dry cloth, (9) 
after dusting with an oiled cloth, (10) after making a feather bed, 
(11) after brushing a skirt in the room, and (12) after brushing shoes 
in the room. 
Note.—The purpose of these lessons is to give directions for the care of the room. 
Stress just those points which seem to be most needed by the different girls. These 
experiments can be outlined on any convenient day and the plates exposed whenever 
the rooms are cleaned. 
Points to be brought out.—A bare floor is more sanitary than a car- 
peted one. In sweeping we should aim to collect and remove dust, 
not to scatter it. A sufficient time should be allowed after sweeping — 
to insure the settling of the dust. An oiled cloth is best for collecting 
dust. Making a bed, brushing a skirt, and brushing shoes all serve 
to distribute dust and bacteria in the room. 
Reference.—Watson, Rules for Cleaning, Cornell Reading Courses, 1 
(1942)> Nox 23. 
Correlation.—English: Write an account of the ways that girls pol- 
lute the air of their rooms unnecessarily. Make constructive recom- — 
mendations. 
