JOURNAL OF CHEMICAL EDUCATION
To the Editor: In the hope of producing some profitable discussion
I wish to express my opposition to the use of standardized tests in chemistry courses, to give+ a few of my reasons for this opposition, and to make some constructive suggestions which may be of interest. These are my personal opinions after more than twenty years of teaching college-level general chemistry, during u7hich time I have used these tests as well as other types. In my estimation these tests do not accomplish the principal practical purpose of an examination, namely, to determine how much of the material taught to the student has been mastered by him and to give him a grade on that basis. ( I am aware of the fact that examinations also serve other purposes.) Such tests invariably contain questions covering material not taught in the course, for no teacher can adequately cover everything in the time usually available. This confuses the student, causes him to waste time in trying to answer these questions, consequently neglecting some that he could have answered.
It is claimed that the results of these tests can be used to measure the ability of a teacher. This is a false and unscientific practice, for the ability of the teacher is only one factor among the several which influence examination results. It is claimed that the results of such tests enable institutions to determine their standing among others; that teachers are enabled to compare their work with that of leading educators; that the questions call the attention of teachers to new- developments in the science, thus helping them to keep up to date. There is a certain amount of truth in some of these claims but it seems to me that these things might be accomplished in some more efficientway. Might not the efforts and funds ;ow devoted to the preparation and distribution of cooperative tests be diverted to the establishment of some sort of channel for the organized exchange of ideas among teachers of chemistry? A "clearing house" controlled by a national committee, assisted by local committees and operated by some full-time personnel, might be established. By means of questionnaires, this "clearing house" could assemble the opinions of large numbers of teachers on such subjects as the content of chemistry courses given for various purposes, sequence of topics, emphasis and amount of time to be spent on various topics, etc. The responses to these questionnaires could be coordinated and studied, the results published, and recommendations made on the basis of consensus of opinion. In the same manner, the opinions of research men and teachers on new theories and developments could be obtained and recommendations made as to the advisability of including these in certain courses.
SEPTEMBER, 1949
Such an organization would provide a place where teachers could send suggestions and ideas not significant enough for separate publication. Collections of these could be published from time to time with credit being given to their authors. In the same manner, examination questions thought by their authors to be original and significant enough to be of use to other teachers might be collected and published. It might be possible to enlist the services of the JOURNAL OF CHEMICAL EDUCATION to serve as the medium for the publication of such material. This is only the germ of an idea which I believe could be expanded into a cooperative system which would be of inestimable value to the teaching profession as well as to students of chemistry.
So1
Hiickel limiting equation holds very well for lower valence types up to about 0.2 p but is not adequate where high valence ions of opposite sign are involved and is not valid for nonaqueous solutions.
To the Editor: I have read with much interest the article on "A simple ketene generator" in the recent June issue. I would strongly recommend that a note of caution be passed on to any who might be inclined to make ketene. Wooster, Lushbaugh, and Redemann, of the FRED Y. HERRON University of Chicago Toxicity Laboratory and Department of Pathology, Chicago, Illinois, writing in the JourUNIVERSITYOF PITTSBURGH nal of Industrial Hygiene and Toxicokgy,29,56 (January, P ~ S B ~ PENNSYLVANIA GH, 1947), review the inhalation toxicity of ketene and of ketene dimer. This article should be required reading, To the Editor: in my opinion, before anyone uses ketene. Briefly, Professor Victor K. La Mer, of Columbia University, they show ketene to be a t least as toxic as phosgene, has been kind enough to point out an omission from and comparable in action. Ketene acts locally on the my recent paper, "The Debye-Hiickel theory and its upper respiratory tract causing deaths from pulmonapplication in the teaching of quantitative analysis," ary edema and the consequent anoxia in the same (THIS JOURNAL, 26, 280 (1949)). I failed to give manner as phosgene. Exposure to concentrations as deserved credit to the work of J. N. Bronsted, in the low as 0.2 mg./l. (116 p. p. m.) for ten minutes have development of the interionic attraction theory. It been fatal to laboratory animals. was Bronsted (J. Am. Chem. Soc., 44, 938 (1922)) who I suggest this reference be given at least as wide pubfist plotted the solubility of slightly soluble salts licity as the excellent article on the generator by Drs. against the square root of the concentrations of various Wang and Schueler. Ketene should be used with salts. Bronsted and La Mer (J. Am. Chem. Soc., extreme caution! 46, 555 (1924)) discuss the work of Debye and Hiickel and plot log f against 4and log S against 4. Bronsted (see Goldrnan and La Mer, J . Am. Chem. Soc., 51,2632 (1929)) also pointed out that the Debye-
