J. S. F. ~ o d e '
I
CR4 and CHEM Study: An Appreciation
The increasing ripples of dissatisfaction with out-of-date curricula (I),which began to he felt in the early 1950's and which reached a crescendo of selfcriticism after the launching of Sputnik I, provided a suitable climate of opinion for the wholesale revision of the curriculum-particularly in science. The growth of the new schemes (8, Q), their extensive trials in the schools (4), and the mechanism of their support by the National Science Foundation (5) have been extremely well documented, and there is no need to go over the ground again. What was wrong with traditional chemistry courses? I think that most of the ills can he summarized under three headings: (1) Courses were too large, built up by a process of accretion, and impossible to finish without a terrible rush; no one seemed to take into consideration that it was no longer possible to know-and even less possible to teach-more than a fragment of any one field of knowledge. (2) Courses were too factual, and textbooks had become unreadable encyclopedias of "essential information." (3) Laboratory work was almost always a tepid demonstration of what the student knew already. Little wonder that the schoolteacher, dogged by factual examinations vital to the future careers of his pupils, inevitably tended to become an authoritarian conveyor of information rather than a more senior inquirer into the mysteries of Nature. There are two fundamental strands which underlie the design of all the new secondary school science curricula: continuous develowment combined with the spirit of inquiry (6). he discontinuity inherent in traditional courses organized as separate topics has been replaced by the continuous development of a limited number of integrative themes (energy, structure, disorder, etc.) to provide coherence within a conceptual framework. Building up such themes must finally bring students to the point where it is only honest to say "we just don't know," so that they become sensitive to the progress of science and in a favorable position to build on new knowledge as it is discovered. I n the lahoratory, attention is focused not on cookbook recipes and mechanical manipulations but on the following questions: To what problems can an answer be sought experimentally? What data are relevant? How may observations be made quantitative? How can the data best he ordered for interpretation? Little attempt is made to conceal the unexpectedness of Nature; at an Harkness Fellow of the Commonweslth Fund of New York, 1964-65.
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early stage nothing could be more damaging than the idea that the rewards of research are empty triumphs, easily come by and easily discarded. The Chemical Bond Approach Project and the Chemical Education Materials Study courses admirably fulfill the spirit of these aims. However, a random sampling of the textbooks (7, 8) cannot hope to give the reader a picture of the systematic nature of these two studies; besides CBA and CHEMS are far more than just t,extbooks. The students' textbook is supported by a laboratory guide, a teachers' laboratory guide, and a comprehensive teachers' handbook. This contains details of approach, underlying philosophy, help with problems which may come up in class discussion, possible demonstrations, and suggestions for further reading. The stress in the two teachers' guides is differently placed: CBA leans more toward helping with teaching problems, while CHEMS indulges in more background discussion. Both courses have complete series of tests available for use every three weeks, a great help to the overworked teacher, who might otherwise slip hack into asking questions which involve only his pupils' ability to memorize. These programs are not an arbitrary selection of one man's views on how to teach, together with his publisher's opinion of what will sell. They are the products of large writing teams of professional scientists and educators: the preliminary material has been tried out in schools, and the feedback from the teachers has been incorporated into successive annual paperback editions before the printing of the hardcover text. I would like to say at once that I regard both courses as a great step forward, a breakthrough in science education. Factual Content and Factuol Errors
This review mould make no sense without a short factual summary of the contents of both coursesEDITOR'S NOTE:Ever since the appearance of the CBA and CHEMS textbooks, we bave been urged to publish book reviews of each one. This has not been practical, chiefly because of the virtual impassibility of finding other than advocates of one program or the other. Further, the textbooks are only a. part of the course materids. The article here presented, we feel, meets admirably the desires of those wanting textbook reviews to be bound into the permanent literature and also meets our o w n editorially-imposed criteria. Dr. Pode spent a year in the USA as a Commonwealth fellow. His wide travels and extended periods of study at Hmvard and California (Berkeley) gave him the opportunity to sample opinions and observe operations. T h i s is a comparative review of two experimental courses; the pursuit of excellence is the only bias observable. A comparable report by a fellow Briton, P. G . Ashmore of Xanchester College, appeared in Science, 148, 1312 (1965).
despite the fact that some readers, after repeated classroom use, will be thoroughly familiar with them. CBA offers a continually widening interrelation of fact and theory in five consecutive sections. Section I starts by describing changes in chemical systems in operational terms, proceeds to operational definitions of elements and compounds, then discusses the composition of compounds in terms of atoms, molecules, and structure. The major theme of the course, "Chemical change is structural change," is introduced here. Section 11, a t inordinate length, explores the relation between matter and electricity, Coulomb's Law, and the idea of the nuclear atom. Section I11 develops the idea of the chemical bond in terms of alternative imperfect mental models. It is notable for an excellent discussion of the relationship between structure and energy, furnished with very clear enthalpy diagrams based on a knowledge of the kinetic-molecular theory. The introduction of periodicity leads to a detailed discussion of different types of bond in section IV. Section V brings out the conflict of attractive forces and random thermal motions with a lucid discussion of free energy and equilibrium, illustrated by acids and bases, for whose behavior various possible models are examined. Kinetics comes next, and finally a chapter on "Water" is used as a vehicle to bring together all the themes developed during the course. CHEMS contains almost the same material (although its development is not usually so extensive), but its arrangement could hardly be more different. The first six chapters are an overview of the course. Heavy stress is laid upon the experimentd approach. An examiuation of the activities of science (observation, search for regularities, creation and testing of models) leads to atomic theory, the mole concept, nature of chemical reactions and stoichiometry, kinetic-molecular theory, phase changes, electron-proton model, and empirical periodicity-all in just over 100 pages. From here until Chapter 18, the course is devoted to the extraction of important chemical principles from relevant experience. Energy changes, kinetics, and dynamic equilibrium are developed successively and used in discussions of solubility equilibria, aqueous acids and bases, and oxidation-reduction. The chapter title, "Why we believe in atoms," leads into an extended discussion of chemical bonding in gases, liquids, and solids. The course concludes with several descriptive chapters, including one each on biochemistry and cosmochemistry; throughout this section it is stressed that however complex the chemical systems under investigation, whether metabolic cycles or geological degradations, the same principles will apply as in the simpler test-tube manipulations. A great deal that would have appeared in a traditional chemistry book has been omitted-nearly always with an increase in the clarity of the presentation. The omission of equivalent weights and molalities only serves to make the mole concept stand out more clearly. The loose thinking associated with a reactivity (as opposed to an electrochemical) series has no place in these rigorous courses. The unfair magic which Dulong and Petit's Law appears to possess-when interpreted with the aid of hindsight-is missing. The bare bones of outdated technologies do not stick up through the soil; this removal of old friends is a ruthless but essential
process. The large number of practicing scientists of great eminence concerned with the design of both courses accounts for the nine major topics in each being the same. They are stoichiometry, atomicity, kineticmolecular theory, periodicity, energy, rates of reaction, equilibrium, bonding, and acids and bases. The fundamental approach of both is identical; the atom is treated as a unit of structure. With the powerful advice available it is unthinkable that it should be otherwise; and consequently the emphasis in both courses is firmly laid on chemical principles rather than on descriptive chemistry. However eminent the contributors, the first hardcover edition of any book always contains factual errorszusually in proportion to the speed with which the final typescript was prepared. The development of CHEM Study went very smoothly; the initial draft was written in six weeks, paperback revisions and hardcover text appeared on schedule, and in the course of five printings of nearly a quarter of a million copies (and several translations) the small errors have been almost eliminated. The same is not tme of the CBA text; very extensive revision was required at each stage because the original central theme, that of the chemical bond, proved unsuitable for early development in the course and was steadily relegated to later and later chapters. The word "bond" now appears for the first time (unindexed) in a heading on page 259 of "Chemical Systems." The first printing of the hardcover version was produced under great deadline pressure and contains numerous small slips which undoubtedly will he corrected in the second printing. The Differing Philosophies of the Two Courses
It is very remarkable that two courses based on the same central theme, and built up on the same nine basic topics, should differ so much in their presentation. CBA is best seen as a reflection of the idealism of Dr. L. E. Strong, without whom it could not have reached its present form. He believes that chen~istryis now in a unique position to introduce high school students to scientific thinking. "Evolving concepts, taught with the appeal of reason" (9) are his classroom goals. Confronted by an immense collection of data, the theoretical interpretations of which are in some respects inadequate,
One factual error that is common to both courses concerns the solubility of calcium sulfate. The literature value is 0.2080 grams CaS04 per liter at 25%, or 15.295 millimoles per liter, giving a value for KePof 2.2 X 10-4. This datum is for the compound CaS04.2H20 a t 25%; the transition point between that compound and CaSOl anhydrous is 42°C. The CHEMS whereas CBA gives its solubility as text gives K,, as 2.4 X 6.2 millimoles per liter. Small errors of this sort are unimportant, but the failure of both texts to distinguish whether it is gypsum or anhydrite which is precipitating in the quantitative calculations which follow is less trivial. Altogether CHElMS has not been lucky in its solubility calculations, for its other choice, copper(1) chloride, is certainly not a happy example. I n the first place, K,, for this compound does rate of not seem t o have been reliablv measured owinz to its hieh u oxidation by air; second, the equation as written (showing ionization to Cut(aq) would inevitably give a pupil the wrong impression about the stability of the copper(1) ion to disproportionation [ K = 108for(Cu2+)/(Cu+)*].
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he believes that even beginning students should be able to comprehend the limitations of some present day theories, and so grasp that science is a process of inquiry that constantly interrelates experimental facts and the necessarily artificial mental models that man constructs from them. Alternative theoretical interpretations of the same phenomena, which are constantly being refined, illuminate the dynamic character of modern chemistry as a developing intellectual discipline. The most dramatic example of this in the CBA textbook is the development of the electrostatic properties of matter in two different ways. If a spherical charge cloud is used as a model for the electron, with the added limitation of the Pauli Principle that only two charge clouds can merge, a convincing picture of the geometry of simple molecules and crystals can be built up. However, such a model provides no interpretation of atomic spectra; for this purpose the wave mechanical orbital model of Schroedinger, in which a limited number of possible total energies are associated with any electron, is invoked. But this model does not account for the tetrahedral arrangement of carbon bonds without the further arbitrary assumption-based on observed prope r t i e ~ t h a torbitals within an atom can "hybridize" when molecules are formed. It is not sufficient for a student to realize that there are two models; he must also appreciate that it is not proper to ask which is the "right" one. CHEM Study on the other hand radiates the cheerful confidence and ready answers of its two chief protagonists, Professors G. C. Pimentel and J. A. Campbell. The infectious enthusiasm of the early writing conferences has been captured in an unpublished history of the development of the course (10). Very early it became clear that four general criteria were being applied in the selection and ordering of ideas for the textbook, and I think it is worth quoting them in full. (1) Is the idea so important that no first course is complete without it? (2) Can the idea be developed honestly at a level comprehensible to high school students? (3) Can it be developed out of experimental evidence that high school students can gather or, at least, understand? (4) Does it tie into other parts of the course so that its use can be reinforced by practice?
Immediately a new note is detectable: these are educational considerations, not chemical ones. Once the decision had been taken to make the first six chapters into an overview section, two things immediately followed. Such a course is much easier to construct, but at the same time it can never have quite the unity of a continuously developing text. The integrative ideas tend to be split up into compartments rather than allowed to expand continuously. The very fact that the new concepts involved in each chapter can be isolated and enumerated in the teachers' guide is an aid to clarity, but a t the same time it robs the subject of the momentum that comes from the constant interaction of theory and experiment. Here one topic succeeds another for reasons which may not be obvious to the students (which could never happen in CBA)-not that this is likely to worry them overmuch, for they are at this time spending the greater part of their working week in the laboratory beginning an outstanding collection of experiments. 100
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The results which the CHEMS student obtains in the laboratory are an absolutely integral part of the course, so great pains are taken to see that he actually does get them. Accordingly the instructions for the experiments are fuller than for those in the CBA laboratory manual, and opportunities for devising personal techniques are correspondingly less. In CBA the instructions for the early experiments are very full, but finally the students are left almost to their own initiative. Very early in the CBA laboratory program, which is, like CHEMS, tightly integrated with the textbook, the "method of continuous variation" is introduced. This I believe to be the most brilliant innovation in either course. By varying the relative masses of reactants over a wide range and allotting one mixture to each student, the law of constant composition can be verified experimentally. Instead of being a boring exercise, stoichiometry becomes a fascinating experimental subject. The method has been cleverly extended to a large variety of systems, but in all of them it retains three great advantages. Each member of the class performs a unique experiment, the teacher does not have to beg the question by supplying the "right" volume of reagents, and any experimental errors will show up in the graph constructed by the pupils themselves in the "post-lab" session. It should now be clear that the two courses go about the business of producing a well-educated chemist in very different ways. CBA attempts to overwhelm him with the logical elegance of the subject without making any concessions, so that intense thought is required. CHEMS, with a clear-cut story line backed up by its magnificent films, seeks to lead him through (and sometimes around) the difficulties by pretending they are not there. CBA has a more sophisticated flavor, especially prominent in its splendid treatment of free energy and electrode potentials; CHEWIS on the other hand is prepared to oversimplify if the structure of the subject is thus clarified. Impact in the Classroom
How will the ordinary pupil react to theye two approaches? To give an accurate answer requires a knowledge of the learning process-three n~onthsin the Harvard University education department was quite enough to convince me that no theory in this field is nearly accurate enough for predictive purpoces. So at this point any review ceases to be objective, and comes to depend on the reviewer's assessment of the students he teaches. Here are four generalizations based on my own teaching experience which I propose to use. First, and most important, is that teenage students hate rabbits pulled out of hats; they always want to be told how the trick was done and feel cheated and disillusioned if they are not. Second, they are not philosophical, and tend to write off semantic arguments as "hair-splitting." Third, they work more by intuition and less by logic than adults think they should. Fourth, their minds are much more flexible than their teachers ever suppose. Many people will not agree with me that this is the way in which a typical high school student's mind works; that is why there is no "right" way to teach any subject, and why it is so important to have several fundamentally different courses available. Both CBA and CHERlS are equally gu~ltyon two
counts of introducing ideas without adequate discussion. The first example of this occurs in their treatments of equilibrium, for which both courses produce brilliant analogies combined with an otherwise excellent discussion. The state of equilibrium is introduced as a compromise between minimum energy and maximum randomness, yet the implication in this, that the potential energy of a system tends toward a minimum, is in direct contradiction of the Law of Energy Conservation on which much st,ress has been laid. It would not have been difficult to explain that all other forms of energy tend to degrade to thermal energy, since this is energy in a more "disorderly" form. The second rabbit pulled out of the chemical hat is the space-filling property of the atom. CBA postulates a kinetic energy to account for it (page 236), but then goes on to associate the kinetic energy with a "charge cloud," which cannot help but be a fundamentally static symbol. A further postulate is then made that compression of the cloud involves a rise in kinetic energy. CHEMS plays down the whole question of the kinetic energy of the electrons in an atom, on the grounds that the topic is too difficult for teachers to explain and pupils to understand. -4tomic volume is treated as a macroscopic property (page 94); the non-collapse of the nuclear atom is presented as an experimental fact which must somehow be connected with the occurrence of stationary states (page 260); orbitals described by higher quantum numbers correspond on the average to the probability of finding the electron farther from the nucleus (page 262). Instead of these arbitrary postulates I would have preferred to see the argument projected one stage further back to the Uncertainty Principle, and the kinetic energy of the electron associated with its localization. The calculation of the lowest energy level of hydrogen, first introduced by Rice and Teller (If), and used with reservations by Feynman (18) could have appeared in the teachers' guide to reinforce the lesson that in quantum mechanics-as in classical mechanicsthe structural arrangement of electrons and nuclei still arises from the opposition of the potential and ldnetic energy. The stress laid on the potential energy approach, and its subsequent elahoration to account for the formation of chemical bonds under equilibrium conditions, yields an intelligible and unified picture of all bonding as "simultaneous attraction of one or more electrons to more than one nucleus"; but its extension to the dynamics of bond formation, especially in the film "Chemical Bonding," is misleading. These criticisms are not meant to imply that I regret the introduction of wave mechanics; my regret is only that both courses have not gone a little further and introduced kinetic energy more honestly. The CHEMS decision to introduce wave mechanics without the prop of the Bohr atom is a brave one, which I believe to be absolutely justified. The temptation to visualize the movement of the electron in terms of planetary motion is all the more dangerous because the idea is so intuitively satisfying. Omitting the Bohr atom while retaining the concept of stationary states is a natural step to take in the elimination of obsolete material. Loss of the Bohr atom is more likely to affect the teachers who had come to depend on it than the pupils who
have not been brought up to believe in fixed paths for electrons. Choice of Style
A cursory glance a t the two textbooks reveals a great difference in literary styles. Professor Pimentel's chatty approach, which gives the impression of dealing systematically and fairly with difficulties as they arise, seems to me a model way in which to address 17-yearolds. The wealth of well-chosen analogies, and the flashes of humor, prevent the text from ever becoming hard going. Great care wm taken over vocabulary in the trial editions. Any words which caused difficulty were removed to locations where the meaning either was specifically explained or was unambiguous from the context; seldom can instruction in chemical terminology have been accomplished more painlessly. Because of the extensive reorganizations between editions, the same clarity has not been achieved in CBA; the textbook appears prolix and diffuse by comparison. I appreciate that, for a course "with the appeal of reason," semantic differences (played down in CHEMS) are important; but their introduction into CBA lends the course a somewhat legalistic flavor. I feel very doubtful of Professor Strong's assumption that the more logical the development of chemistry can be made, the more appeal it will have in the classroom. Certainly a strictly logical approach leads to great difficulties; for chemistry, in isolation, is not a logical subject. That is why chemistry as a science got started so late in history, and why the nineteenth century developments appear so turtuous. The reason is that elements and compounds are the concepts used to interpret observed chemical phenomena, but these concepts in turn are traditionally defined in terms of the changes they undergo. There are two ways out of this circular argument. Either the physical evidence for the atom can be built up and used to give an independent meaning to the word element, or else an operational definition of elements and compounds must be sought. Professor Strong defines an element as "A substance which always enters into a chemical change to produce a single product, interconvertible products, or products of which only one is a compound of the substance" (18). Consider the action of the element chlorine on benzene. I doubt very much whether there are any practical ways of interconverting the various isomers of benzene hexachloride. What Professor Strong means of course is "theoretically interconvertible," but he cannot say so because the definition would then no longer be nperational. Rigorous definitions play a big part in CBA. I question the wisdom of this, since so often the more rigorous the definition, the more it divides Nature into watertight compartments which have no reality, but only reflect the desire of the human mind for tidiness. Any chemist who has conscientiously tried to define the term "complex ion" will have realized the futility of the task before he is finished. However, this insistence on rigor can have unexpected and beneficial results. The impossibility of proposing an all-inclusive yet meaningful definition of oxidation-reduction causes CBA to deemphasize the whole topic, summing it up thus: "Oxidation-reduction is a bookkeeping procedure based on nothing but a set of rules chosen for convenience" Volume 43, Number 2, February 1966
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("Teachers' Guide;" Section 13-13). CHEMS on the other hand uses whichever of the familiar alternative definitions seems most appropriate on the various occasions when the topic arises. Perhaps the most just comment that can be made about CBA as a whole is that it is a course "for average students and exceptional teachers." It has been taught successfully in a very wide range of circumstances besides in the eleventh grade: to ninth graders in Chicago: to junior college students, to freshmen in a four-year college, to t,eachers in training colleges and summer institutes. I have seeu for myself the great enthusiasm it arouses in teachers and their students; certainly no one who has once been exposed to CBA could ever revert to teaching a purely traditional course. Wordy and diffuse though it is in places, "Chemical Systems" was conceived a a complete break with the past. No compromise was made to make it easy to teach or easy to sell; the result is a seminal work that no future designers of chemistry courses can possibly ignore. Without sacrificing the general aims of the new curricula, CHER'IS is a much less revolutionary course than CBA It in an extremely practical solution to a national problem-the improvement of high school chemistry teaching in America. It is undoubtedly easier to teach than CBA, and a summer institute is not so vital in the preparation of a teacher who is thinking of switching from a traditional course. "Chemistry, an Experimental Science," is much more a textbook in the ordinary sense of the word, and students would have a good grasp of the course with a careful reading of this alone. Wider Educational Problems Raised by the Design of CHEMS and CBA
By concentrating exclusively on the activities and mental processes of the academic chemist, the applications of chemistry in everyday affairs necessarily occupy but a small proportion of both courses. I do not in the least lament the disappearance of details of manufacturing processes. Any automobile mechanic knows that constant retraining is necessary to keep up with technological advances, which become obsolescent almost before they are on the market. For this reason, the depreciation on most chemical plant facilities is 20% per year. However, the inevitable implication that chemistry is an exclusively academic pursuit must be avoided a t all costs. The chemiral industry is an admirable example of the problems and rewards of applied science and technical training. The academic chemists insist that these considerations only obscure the scientific principles that they are trying to put across. Revertheless I should he extremely unhappy to see the applied industrial aspects of the subject drop out of the school curriculum altogether. Again, chemistry is a splendid way to introduce the teaching of economics. The subject is loaded with examples of the strategic importance of raw materials, the laws of supply and demand which apply to them, and the pressures which cause well-tried materials to be superseded. I agree that these topics are not relevant to chemistry as an experimental science, but they should not on these grounds alone be jettisoned wholesale from the school curriculum. 102
Journal of C h e m i c ~ lEducation
Neither course, wisely, follows the historical order of events in the development of modern concepts. The treatment in many elementary texts of the growth of the atomic theory either misleads readers by trying to adhere to something near the truth, or by oversimplifications makes all the eminent chemists between Dalton and Cannizzaro look hopelessly stupid. The excellent fullpage biographies of famous chemists in hoth the new courses is a far better approach to the history of the subject, and prepares the pupil who is fascinated by it for the time when he can undertake a graduate study. The problem of classroom demonstrations introduces a dilemma. Both courses include a limited number in the teachers' guides; but how is their use to be reconciled with the spirit of inquiry so much stressed in the development of all the new curricula? Pupils undeniably enjoy them, but is it right for the teacher to encourage this attitude? Shouldn't the answer rather be "Into the laboratory and find out for yourselves"usually a very time-consuming process. CHEM Study achieves a compromise: ". . . experimental theme is supported by a number of films to provide experimental evidence that is needed but not readily available in the classroom because of inherent danger, rarity, or expense." The content of the films is on the whole excellent; the presentation is first-class with a really professional finish. A number of them are recommended by CBA in its teachers' guide. However, the spirit of inquiry has little chance of surviving in a onesided argument with a man on a screen. The exact place of demonstrations in the new curricula needs to he thought out more clearly. Very few of the hundreds of teachers whom I have asked have ever managed to finish either course, even though CBA is now shorter by a whole section of descriptive work than was originally intended. I t is easy to say that it is better to be too long than too short, and that in any case most teachers manage just to reach the descriptive chapters; but surely it is precisely here that the students get most value when they see that the principles that they have developed so laboriously are very widely applicable in unforeseen situations. The weakest part of both courses is the section on energy, where they stray into physics; the obvious solution is an integrated two-year course. Amalgamations of PSSC and CBA, and also of PSSC and CHEMS, with a consequent shortening of both courses where they overlap, are being tried out in the Portland Public School System. The 85% re-enrollment for the second year is an impressive vote of confidence from the pupils. The support given by hoth courses to curriculum experiments of this type has given rise to a widespread fallacy-that a brand new course containing the best of hoth CBA and CHERlS will shortly appear. This eut,irely neglects the basic differences between the philosophies of the two courses. CBA is committed to a continuous re-examination of alternative concepts in the light of experimenl, whereas CHERlS (after explaining the uncertainties inherent in all measurement) bases one good model on experimental findings and incorporates it into a single finite structure for explaining all chemical data. On the one hand CBA is a splendid introduction to the imaginative nature of science, but its reservations make it difficult to teach didactically,
and it is more complex in its applications to specific chemical situations. On the other hand there is CHEMS, with all the attraction of certainty, rightly confident in its power to bring order into present chemical chaos. On the trivial level it might be possible to pick out the best analogies and experiments from each, but a choice must inevitably be made as to the philosophical framework in which these are to be displayed. I hope I have made it clear that the two courses contain all the topics relevant to modern chemistry, but have very different structures and objectives. As I travel around to different schools I am frequently asked which is the better; such a question reveals the questioner's lack of information. The choice of one rather than the other is a matter of the personal preference of the teacher and the degree to which he is prepared to commit himself. CBA requires a greater degree of commitment and a greater mental upheaval; and so its converts tend to be more fanatical in its defense than are the CHEMS men in justifying their system. I n the best schools three chemistry courses should be available: CBA, CHEM Study, and an Advanced Placement course to cater to those who have been fired with enthusiasm by either of the others!
Literature Cited (1) CLAW, L. B.,J. CHEM.EDUC.,32,141 (1955). J. S., "The New School Science," American (2) MARSHALL, Association for the Advancement of Science, Washington, D. C., 1963, p. 2. R. M., J. Research in Science Teaching, 1,27 (1963). (3) GANGE, (4) ATKINS.J. M.. J . Research in Science Teachino. 1.129 11963). . , i5j "Science Co&e Improvement Projects," National Science Foundstion, Washington, D. C., 1964. (6) STRONG, L. E., J. CHEM.EDUC.,39,126 (1962). (7) PIMENTEL,G. C., Editor, "Chemistry, an Experimental Science," 1st edition, 5th printing, W. H. Freeman & Co., Ssn Francisco, 1963. (8) STRONG, L. E., Editor, "Chemical Systems," 1st edition, 1st printing, McGraw-Hill Book Co. (Webster Division), New York, 1964. (9) STRONG, L. E.,Chm. andEng. News, 43, February22,1965, p. 128. (10) MERRILL,R. J., Editor, "A History of CHEM Study," CHEM Study Headquarters, University of California, Berkeley, Calif., 94720. (11) RICE, F. O., AND TELLER,E.,"The Structure of Matter," John Wiley & Sons, New York, 1949, p. 7. R. P., LEIGHTON, R. B., AND SANDS,M., "The (12) FEYNMAN, Feynman Lectures on Physics," 1st edition, AddisonWesley Publishing Co., Reading, Mass., 1965, Val. 1, Section 38-6. L. E., Editor, "Chemical Systems" (op. cit.), p. 31. (13) STRONG,
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