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I believe most problems will be dropped with the answer 144°F. instead of 68°F. For the past ten years I have been using and teaching a conversion scheme that seems to satisfy the need as well as to satisfy the student. The standard point of conversion in this scheme is -40°C. equals -40°F.
Therefore, if I were to change 20°C. to F., the plan is to add 40, multiply by 9/5, subtract 40 and the result is 6S°F. Also to change 6S°F. to ?T., the plan is to add 40, multiply by 5/9, subtract 40, and the result is 20°C. To state these plans in algebraic formulas
for the algebra student is advisable. This little puzzle of changing temperature scales in science classes causes very little fear and worry for students and teachers in our high-school science department. Since the standard texts use the old 32' plan of conversion, the origin of the -40' plan cannot be indicated, in spite of the fact that it has been used for ten years producing successful and pleasant results. HERMAN W. WOODS
A SHOW WINDOW FOR THE CHEMISTRY DEPARTMENT We hear it said that every teacher must be a salesman, selling his subject. What more legitimate, then, than a salesman's show-window? I wished for one for several years. Interesting things are brought, or develop on o w hands, and only a favored few see them ordinarily. Last year I removed a "dead" exhibit of zinc plant "intermediates" from a case in the hallway outside my door, put in a lamp-bulb, and every few days introduced a "live" exhibit. There were a "chemical garden," surface tension boats, Geissler and X-ray bulbs which worked with a push-button, a rock that floated on water (volcanic tufa), a density exhibit with mercury,
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FEBRUARY, 1931
iron, carbon disuUide, and so on. The students liked it. They talked about it and asked questions. Isn't that a desirable result? Accordingly, in our new high-school building, provision was made for i t in the form of a real display window. It opens from the stockroom just like a show window in a store, is easily accessible for changing exhibits, presents a neater appearance than a case standing in the hallway as the old one did. and the light i t affords makes a bright, inviting spot in what would be otherwise a dark stretch of hall. Exhibits are not difficult to furnish and all the students in school get around to see what we have. RICHARD L. FELDMAN S ~ m r o aHzan Scnoor. DONOX*,
PXNNI.
