CHEMISTRY TEACHING FOR GENERAL EDUCATION1 WILLIAM HERED Indiana University, Bloomington, Indiana, and University of Chicago, Chicago, Illinois
1s THOSE inbtitutions having no distinct program of general education the besnning course in chemistry must assume responsibility for representing science as a significant aspect of intellectual activity. The need for a widely educated citizenry, rather than the narrow specialists of Plato's ideal, becomes increasingly obvious as the complexities of life grow. A real appreciation of the methods, aspirations, and limitations of science has become au essential ingredient of general education. Too often, under the pressure of covering as much material as possible in the ever-tightening curriculum, teachers lose sight of this basic obligation. The presence of qualitative analysis, for instance, in the first year's work, has little justification except, perhaps, as training for future chemists; the resulting compression of more vital matter is extremely unfortunate. The basic problem consists in emphasizing science as a way of thinking, without sacrificing essential content. One solution would allow the general aspects of science to be taught in a separate course, thereby permitting concentration on content in beginning chemistry. The wealwess of this solution is fundamental; science has no meaning divorced from context. Clearly the rigid discipline of a particular subject matter must be the basis for any fruitful exemplification of science. Can one afford the additional time required for increased emphasis on science in view of the other responsibilities of the beginning course? The answer is that time must be found, eveu a t the risk of doing away with some of the sacred cows of tradition. Numerous topics can be excised without harm either to preprofessional training or t o education for lie. While the most significant effortb in the direction of education in the meauing of science are represented by the integrated studies, there is no reason why such efforts cannot be made successfuUy within the format of the first-year specialized course. The content need not be revised drastically; the major alteration would be in the way of viewing the content. A critical and inquiring attitude toward the problems encountered and constant vigilance for lacunae in the reasoning process should provide the proper atmosphere. The textbook or syllabus should exhibit the thought processes of the investigators, as does the physics text of Taylor (1). Much can be learned about possible avenues of approach from an examination of current experiments in the integrated curricula. A brief r6sum6 of several technioues in present use may be of value in adapting conventional materials for this approach.
One technique is that found in the much-castigated
',survey" course. Integration is its professed aim, al-
though compartmentalization usually is present. At its worst the survey is superficial, trivial, and unscientific, but a t its best its promise exceeds that of the specialized courses, since the survey can draw upon a wide range of subject matter for illustrations of scientific investigation. A valuable textbook in the survey field is that of Krauskopf (2). More radical departures from convention result from the application of the premise that students best learn about science by study of original reports of scientific investigations. Two implementations of this premise may be mentioned here, that of Harvard University and that of the University of Chicago. The Harvard method is based upon the principles outlined in Conant's "On Understanding Science" ($), and utilizes the "Harvard Case Histories in Experimental Science" (4) as the basis for .lecture and discussion. Each of the "Case Histories" centers about a particular problem arising in the development of science and consists of a constellation of excerpts from original reports interpreted by considerable editorial commentary. While superficially similar to the Haward approach, that of the University of Chicago differs a t salient points. Instead of excerpts from original articles, entire papers are studied wherever possible (6). Editorialization is limited to rewording for clarity, explanation of terms, and filling gaps; practically no evaluational material is inserted. Since understanding is regarded under the latter plan to arise if student-teacher interaction is maximized, the absence of "official" interpretation has the purpose of encouraging free discussion. Obviously a greater variety of source material is possible under the Harvard system, but from the viewpoint of education as an active process on the part of the learner, the Chicago technique may he on surer ground. Quite aside from the question as to possible overemphasis of the historical or philosophical aspects of science by these methods, two basic limitations appear. One is the difficulty of exhibiting a sufficiently broad panorama of content, thus necessitating extreme care that the choice of papers be truly representative. A more serious limitation lies in the fundamental fact that scientific reports are couched, for the most part, in terms far more suitable for fellow scientists than for students. The number of usable papers is thereby severely restricted. Moreover, those which are usable are often "old," since simplicity of concepts and quantitative manipulation is an attribute of the younger 1 Presented a t the 123rd Meeting of the American Chemical phases of a science rather than of a mature science. Society, Los Angelm, California, March 16, 1953.
DECEMBER, 1953
Henre a common criticism of courses based entirely on original reports is that the content of present-day science lacks adequate representation. One implication of the foregoing is that presentations of the type exemplified by the Taylor and Krauskopf texts may be combined profitably with intensive study of a few key papers. A number of such papers have proved themselves highly useful for classroom discussion. Among these are Lavoisier's "Treatise on Chemistry," the Dalton, Gay-Lussac, Avogadro, Cannizzaro, Mendeleev sequence on the development of the atomic molecular theory, the van't Hoff and Arrhenius treatments of colligative properties, and Clausius' kineticmolecular theory. It is entirely possible, however, to impart the essential characteristics of the scientific method without recourse to such materials if the classroom procedures reflect the scientific viewpoint. Each important hypothesis should be accompanied by supporting factual evidence, and pains should be taken to exhibit all of the links, both strong and weak, in the chain of validation. Bald and unsupported statements such as "We know that the atom is mostly empty space," violate the spirit of inquiry and cannot but leave the student unsatisfied and uninformed. Of course, not all theories require exhaustive validation; some rest on an irreducible core of abstruse physico-mathematical principles and others may not be important enough for such development. As an illustration of a way in which conventional materials may be used to illuminate the facets of scientific method, class discussion on the kinetic-molecular theory of matter might proceed as follows. After a preliminary groundmg on possible definitions of matter and its states, alternative methods for attacking the problem of its constitution are discussed. The suitability of gases for this study, in consideration of their similarity in physical behavior, is developed. Since the theoiy proposed by students in explanation of expansibility, diffusibility, etc., is usually the currently accepted one, an opportunity is afforded the instructor to assume the guise of a devil's advocate by proposing an alternative postulate. He may hold, for instance, that gases are made up of particles which are always in contact and which are capable of expansion and contraction under certain conditions, his purpose being to stimulate thinking. The first reaction to such an absurd idea is usually an emotional afirmation in the "correctness" of the kinetic-molecular theory. Shortlv. however, even the dullest student realizes that facts, not faith, are required here; out of the confusion should come the realization that objective evidence decides scientific issues. ks the discussion continues, the need for more precise information about gases becomes apparent. Here the law PV =kT is developed as a class demonstration. A check on the validity of the kinetic-molecular theory is shown to be possible by deriving a quantitative prediction from the theory and comparing this prediction with the empirical relation. The instructor now exhibits the %muZ,exercising derivation of the equation PV =
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great care to furnish the essential physical concepts and definitions involved and emphasizing the underlying assumptions of negligible molecular volume and interaction. The similarity of the theoretical and empirical equations is noted. Complete correspondence of the two equations is seen to require an additional assumption, namely that absolute temperature is the outward manifestation of molecular translational kinetic energy, thereby leading to what seems to be fact-getting without experiment. Skillful guidance of the discussion should now lead to the realization that such assumptions are pot amenable to direct proof but may be validated through their consistency with other facts. At this point the class is apt t o feel quite self-satisfied and certain that the Q. E. D. has been pronounced. The illusion is promptly dispelled by exhibiting data on carbon dioxide at high pressures and low temperatures. Apparently the assumptions underlying the kinetic equation must he re-examined and modified. AUowance for molecular volume and intermoiecular attraction is seen to provide corrections which are of the proper direction and magnitude. Thus deviations of gases from the gas laws can furnish additional support for the kinetic theory. The interplay of ideas during the give-and-take of informal discussion furnishes a splendid learning situation. Naturally, the instructor's preparation for sessions of this kind is far more demanding than that for the oneway flow of the lecture, but the sense of accomplishing something worth while is its own reward. The intellectual growth of the student is almost palpable. A note of caution must be sounded, however. Unless the course examinations truly reflect the complex objectives of instruction, much of the gain may be nullified. Students are realistic above all else, and soon refuse to struggle with the less obvious aspects of scientific reasoning in the classroom if the examinations test merely for pedestrian recall of facts and solution of hackneyed numerical problems. The importance of high-level examinations cannot be overemphasized. In the last analysis quality in teaching rests with the individual teacher. Even the murkiest materials can be illuminated to some degree by a competent and enthusiastic personality. Nevertheless there is little sense in imposing unnecessary burdens of understanding on the student. Perhaps this paper may serve by suggesting ways of facilitating the learning process and the acquisition of desirable attitudes toward science. LITERATURE CITED (1) TAYLOR,L. W., "Physics, the Pioneer Science," Houghton MiJ3inCo., Boston, 1941. (2) K ~ a a s n o ~ rK., , "Fundmentals of Physical Science," 2nd ed., MeGraw-Hill Book Ca., Inc., New York, 1948. (3) CONANT,J. B., "On Understanding Science," Yale University Press, New Haven, Conn., 1951. J. B., Editor, "Haward Case Histories in Expori(4) CONANT, mentd Science," Harvard University Press, Cambridge, n,roor '.&--.
(5) y - h e ~~t~~~ of ~
~ t Structure t ~ ~and: Transfomatiotions," University of Chicago Press, Chicago. Ill., 1952, 1953.
