LETTERS To the Editor: In teaching stereochemistry and the strain theory I have found that the usual carbon models have a disadvantage in that the student sees them only for the brief period of the demonstration in the classroom and does not become familiar with them. Also an exhibition of some of the structures in a showcase for a week or so has not proved entirely satisfactory. Much better results were obtained when I gave the construction of such models as an assignment. I include some photomaohs of these cardboard models with this letter.
High-School Ph.D.'s T o the Editor: A comparison of the "College chemistry test in the Armed Forces, Institute"' with the "High-school chemi s t test ~ of the Armed Forces I n s t i t ~ t e "is~instructive and significant. These tests were devised by carefully selected groups of teachers of each respective type, who consulted standard texts and other authoritative sources. The tests, which were also tried out on large monos of students in various localities. betrav the &&onal philosophies and limitations of both Goups of teachers, and explain the woeful confusion eugend a d in the minds of many students of chemistry by the lack of any logical, coherent, cooperative policy to connect high-school chemistry teaching with freshman college chemistry courses. A few of the more outstanding differences may be stated:
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