Behavioral Objectives To the Editor: I would like to take issue with the Provocative Opinion expressed by Robert L. Wolke (University of Pittsburgh) in the February 1973 issue of this Journal. He seems to give the impression that behavioral objectives are useless. When he says that the only meaningful behavioral objective of a science course ". . . is the student's ability to crack that (n + 1)th problem after he has left the course . . .,"he is most assuredly correct. He says that this ability can not be measured. It certainly can not be measured with the behavioral objectives that he gives as examples: ". . . the student should be able to solve, to compute, to write, to define, to select, to list, to match, to express, to describe . . . ." These behavioral objectives require only memory. The ability of students to solve new prohlems can he measured if the behavioral objectives are worded properly. For example: the student will have the ability to generalize from data, discuss critically, predict, propose reasons and defend them. formulate hvootheses. etc.l ". How can one measure understanding or appreciation? Thev can be evaluated onlv on the basis of behavior. Students in science courses must be asked questions which require them to think instead of "spit hack" memorized information. This is essentially what Mr. Wolke says. But, behavioral objectives are necessary because if the teacher does not have a clear idea of what he expects the students to do, then how is the poor student supposed to guess? -
Another Salvageable Method for Treating Mercury Spills To the Editor: The recent appearance of two articles [De Nardis and Maslanka, J. CHEM. EDUC., 50, 336 (1973), and Idoux, J. CHEM. EDUC., 50, 739 (1973)) concerning methods of dealing with small mercury spillages has prompted me to report the following method, which I consider would he superior to the above two in most situations. The method employs a small rectangle (about 5 x 10 cm) of 0.1-mm copper foil, one edge of which has been dipped briefly into a dilute solution of mercuric nitrate in order to amalgamate the surface. The surface on which the mercury has been spilled is then swept with the copper foil, with the amalgamated edge making a fairly low angle with the surface being cleaned. A surprisingly large amount of mercury adheres to the copper, and can be collected by simply tipping the copper foil over a beaker so that the amalgamated edge sits vertically above the mouth of the beaker. Most of the collected mercury then runs off the foil into the beaker, and the above procedure can he repeated until all the spilled mercury has been collected. The collected mercury can then he pooled with other mercury residues for subsequent purification by distillation.
G. A. Bowmaker The University of Auckland Auckland. New Zeeland
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'Romey,
William D., "Inquiry Techniques for Teaching Science," Prentiee-Hall, Ine., Englewood Cliffs, New Jersey, 1968,
Drake University Des Moines, Iowa 50311
Larry Youngberg
An Analogy for Teaching Hybrid Atomic Orbitals To the Editor: I read with interest the article by Chao-Yang Hsu and Milton Orchin entitled "A Simple Method for Generating Sets of Orthonormal Hybrid Atomic Orbitals," (J. CHEM. EDUC., 50, 114 (1973)). I heartily concur that this technique can easily he undentood by students. In 1965 I developed and used this same approach to the description of hybrid atomic orbitals as a means of elevating the concept of hybridization and resonance out of the status of white, black, and gray paint and horses, donkeys, and mules. For those who would like a ready source for classroom use this treatment appears in a somewhat more simplified form in the introductory textbook, "The Chemistry of Matter," (Houghton Mifflin Co., Boston, 1970), written by the undersigned.
Reducing Benzene Hazard To the Editor: The letter by Bull, [50, 665 (1973)l concerning sodium bis(2-methoxy-ethoxy) aluminum hydride brings to light a relevant problem concerning the use of benzene in laboratory situations. As a supplier of this material under the trade name Vitride reducing agent, we are aware of the health hazards when using benzene or benzene solutions as a laboratory reagent. Recognizing the hazards of benzene, we also supply this product in a toluene solution which carries the trade name Vitride-T. In addition to the safety aspects of using toluene in place of benzene, Vitride-T reducing agent is useful a t much lower temperatures than Vitride reducing agent in benzene. We would certainly recommend that where the use of Vitride reducing agent in benzene would be considered hazardous or where suitable laboratory facilities for its use were not available, that the Vitride-T he used. G. S. Grau
J. B. Pierce Lowell Technological Institute Lowell, Massachusetts 01854 426
/ Journal of Chemical Education
Eastman Kodak Company Rochester, New York 14650
