Chemical Education Today
Literature Cited
Education and Students' Interest in Chemistry Can Be Improved I really enjoyed reading the captivating article written by Alex Johnstone (1): “You Can't Get There from Here”. For many years I followed the monkey's logic: notwithstanding the huge amount of time that I devoted to teaching, the benefits that students received, according to their opinions, was disappointingly low. Fortunately, I was able spend some time at the University of Glasgow with Alex Johnstone, in the Centre for Science Education. While walking and talking with Alex in the Scottish highlands, I realized I had to change the chemistry curriculum that I was using to teach engineers. I realized that I was covering too much material in an unproductive way, but what could I remove? I decided to skip colligative properties, although that was not an easy decision. I was so used to regarding this as fundamental content (the monkeys again), but it turned out to be no great loss. Something also was wrong with the way I taught problem solving. I taught the solutions to the problems one step at a time, explaining the various steps. Maybe it was an elegant explanation of the solution, (the way one can find in the textbooks), but it was a procedure that did not help students learn how to approach problems in a fruitful way. This was because “Textbook solutions to problems and solutions presented by teachers in class are almost always efficient, well-organized paths to correct answers. They represent algorithms developed [by experts] after repeated solutions of similar problems” (2). I was not aware that the process I was using was difficult for students to understand, particularly those who were seeing these strategies for the first time (3). In my last course, I refused the “monkey” point of view and started with some organic: my students enjoyed the course and several even showed enthusiasm! I have had much greater success in my classes without teaching the solutions of the problems, but asking my students to solve problems in cooperative teams. My task is to grade the proposed problems, considering their cognitive load (4), to suggest some strategies for facilitating the solutions of problems, and then to discuss the errors. From the 43 students who reached the end of the course, about 35 of them attended lectures regularly, I received hundreds and hundreds of e-mail messages from the students as they worked on the problems and, in response, I sent them more than 600 e-mail messages. In the 50 h of the course, more than 5000 solutions of problems were submitted by the students, which I collected and corrected. On average, 122.0 individual problems were attempted. Some students attempted only 30 problems while others tackled 433, with a standard deviation of 83.7. Some students solved difficult problems in an original and creative way. A few years ago, a student gave up the study of engineering and went to Bologna to study chemistry! All of this is based upon an approach arising from taking cognizance of the work described in Johnstone's paper. Further thought and work may enable us to change the title from “You Can't Get There from Here” into “Yes We Can”.
r 2010 American Chemical Society and Division of Chemical Education, Inc.
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1. 2. 3. 4.
Johnstone, A. H. J. Chem. Educ. 2010, 87, 22–29. Herron, J. D. J. Chem. Educ. 1986, 63, 528–531. Bodner, G. J. Chem. Educ. 1987, 64, 513–514. Johnstone, A. H.; El-Banna, H. Stud. Higher Educ. 1989, 14, 159–168. Liberato Cardellini Dipartimento di Idraulica, Strade, Ambiente e Chimica, Universit a Politecnica delle Marche, 60131 Ancona, Italy
[email protected] DOI: 10.1021/ed100091b Published on Web 08/30/2010
Pauling's s-Character Calculation In his book, The Nature of the Chemical Bond (long considered “the bible” by many chemists), Pauling related the coefficient of s-orbital contribution, R, in the wave function of an s-p hybrid orbital to bond energy, B, and promotional energy, Ep - Es (1). For his result, he gives an approximate answer (“in which terms in powers of R higher than the square have been neglected”), eq 1. B ¼ ðEp - Es Þð31=2 R þ 3R2 Þ
ð1Þ
In addition to being an approximation, it is a quadratic equation, which makes the solution somewhat (though by no means fatally) inconvenient and makes it possible that there will be two roots. In a failed attempt to duplicate Pauling's derivation, I found instead an exact solution for R, eq 2. B ð2Þ R ¼ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 3ðEp - Es Þ2 þ 6ðEp - Es ÞB þ 4B2 Anyone upon whose instruction or investigation this aspect of Pauling's work bears may find this solution relevant. The derivation, for anyone interested, is available as supporting information. Literature Cited 1. Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell University Press: Ithaca, NY, 1960; pp 120-123.
Supporting Information Available The derivation of eq 2. This material is available via the Internet at http://pubs.acs.org. Ben Ruekberg Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881
[email protected] DOI: 10.1021/ed100641w Published on Web 08/27/2010
pubs.acs.org/jchemeduc
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Vol. 87 No. 11 November 2010
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Journal of Chemical Education
1137
