Re-examining Some Chemical Truisms
Thinking about How We Think
Although the training of scientists orients them strongly toward examining every new "truth" presented to them and they pride themselves on their objectivity, the body of scientific knowledge is so large that many ideas and methods that were once effective and appropriate can continue in common usage lonr after a re-examination would have pointed to their m o d i f i c a t k or replacement. I t thus becomes as important for the scientific community to periodically review all those thines knows" as it is to rieorouslv examine ~-~ u which "evervbodv " " " new data and theories. This re-examination of a well-accepted truism of chemistry is central to four articles on diverse topics which appear in this issue. Each author has looked a t his field of interest with a skeptical eye and found a new insight, method, or approach which he shares with our readers. In "Ternary and Quaternary Composition Diagrams" MacCarthy (page 922) examines the entire problem of graphing three- and four-component systems in a manner which is easy to visualize and read. He reviews the methods for reading these diagrams and points out that the easiest mode is the one least used. He then goes on to the various types of diagrams and shows that the equilateral triangle, the most commonly used system of representing ternary compositions, does not possess certain advantageous features of the far-less-used right isoceles triangle. These advantages hecome even more pronounced when he considers quaternary systems. B r y a n t (page 933) states that it is common jargon to talk about slow or fast processes in relation to the "NMR time scale" as if such a time scale had been carefully defined and agreed on by all. He asserts that, while there may have been some validity in such a concept when NMR was new, "the trulv multinuclear character of NMR soectroscoov and the ready access to NMR relaxation rates by Eimmercial instrumentation todav makes anv blanket statement.. . imprecise a t best and more often n i t completely meaningless." He then examines each of the physical or chemical processes associated with NMR spectra and correlates them to their time-scale ranges. When aromatic substitution reactions are introduced in beginning organic courses, a strong impression is given that incoming suhstituents only will, or are most likely to, replace ring hydrogens rather than attack an already substituted carbon. Traynham (page 937) points out, however, that "When You've Said Ortho, Meta, Para, You Haven't Said I t All" and that the ipso position competes effectively with the unsuhstituted positions in many of these reactions. He presents a range of examples for nucleophilic, electrophilic, and free-radical reactions where the ipso position is an important, predominant, or even exclusive site of reaction. If data are the building blocks of theory, then units are the mortars which hold them together. Scientists can become so engrossed in building their theoretical edifice that they start taking the bricks and mortar for granted. Wadlinger (page 942) discusses several instances where a critical re-examination of the use, or lack of use, of units should be made. He advocates the introduction of the descriptive unit wave to make many relationships, such as the Planck-Einstein equation, less open to misinterpretation and proposes the adoption of the radian as a fundamental unit. The difficulties and misapprehensions which occur when these and other units are not used or are used improperly are examined in detail.
Understanding an idea and understanding how one has learned that idea are two very different things. For the welltrained teacher of chemistry the first is a given, hut it may not even occur to this same teacher to explore the second. If this teacher is in charge of an introductory course whose students' abilities in abstract thought are undeveloped, the entire semester may be fraught with missed concepts and missed opportunities. Teachers, no matter how well-versed and wellprepared for their classes, need to give thought to how abstract concepts are learned by the neophyte and apply this knowledge when designing their presentations. Those seeking information from those who have formally studied this problem will find a wealth of it in this issue.
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914
Journal of Chemical Education
aspects of the learning process.in the "~ntroduction"Herron (page 947) summarizes the two dominant learning theories discussed by Renner and shows how one is more consistent with what we consider to be the nature of science and science education. Reif (page 948) makes suggestions, based on studies of cognitive processes, on how chemists can teach problem solving more effectively. Rowe (page 954) examines the lecture in terms of what is known about the rate a t which the human mind can absorb information and makes proposals for improving reception rates. Applying learning theory to course construction is not a new idea, and the new educational technology has already gone through several iterations. Kulik (page 957) evaluates the data obtained on some of these technologies (such as PSI, computer-based teaching, and nroarammed instruction) and uses meta-analvsis to comoare their effectiveness. Another article which touches on the orohlem of the limit of what the mind can absorb in a given interval is the Nyholm Lecture hv Johnstone (oaee 968). Johnstone investinated difficult-tb-grasp topics chemistry and analyzed them in terms of how the short term and working memories function. This process led to strategies for teaching these topics which would avoid information overload.
Polymer Chemistry The case has often been made for the incorporation of more polymer chemistry into the undergraduate curriculum, but, like the weather, it has been a topic which most have been content to talk, rather than do something, about. The ACS Joint Polymer Education Cammittee, however, decided in 1979 to translate this dictum into action. Through the formation of Core Course Committees for each of the major subject areas, reports have been generated which make concrete suggestions and give specific examples of materials which the teacher can adopt directly into his or her syllabus. This month we begin the publication of these reports, which will appear periodically as a mini-series, with an introduction to the project (page 971) and the report for introductory general chemistry courses (page 973). In addition, Mathias (page 990) outlines ideas for implementing a one-semester undergraduate polymer laboratory course and includes an extensive bibliography of experiments and reference articles
