provocative opinion Chemistry Instruction: Observations and Hypotheses Betty Wmck and Jesse Reinstein University of Wisconsin-Platteville, Planeville, WI 53818 After more than 40 years of combined experience teaching general chemistry t o students with varying backgrounds, we are all too aware of our shortcomings and misconceptions ahout teaching. I t is not that we have lost our initial idealism; i t is simply that we have become more realistic concerning our expectations of the student and the student's perceptions of our instruction. We believe that the hwotheses nresented in this Daoer regarding student-teacherattitudeke not applicabletdall students taking chemistry. There are still those hard-working students who make teaching worthwhile and an emotionally rewarding profession. However, we have found that our hypotheses seem t o apply t o an increasing number of students. Being human, the student-teacher relationships that we have experienced have had pronounced effects i n our attitude toward individuals, classes, and teaching. Hwotbesis 1 can he stated as follows: The amount of effortput forth by the students is inuersely proportional to their nrior exoosure to the material. Two of our introductory general chemistrycoursesare taught on theassumption that the students have not had anv hieh school chemistrv. For several weeks we spend considerable time in lecture &d laboratory discussing concepts such as the metric system, density, structure of the atom, symbols and names for elements and ions, and moles. I t is not surprising to see students sitting back looking bored because a large percentage of them have taken high school chemistry. However, performances of too manv students with nrior work in chemistrv on examinations and in laboratory is far from what i t shouli be. Some students will perform well on the first test because of their background, but they will have formed the habit of not studying. When "new" material comes along, they cannot or will not make the adjustment. I t is our premise that the more the students think thev know bv virtue of nrevious exposure to the material the lekeffortthey devote t o the subject. We have also discovered that eood students who have never taken a chemistry class will Gt in a significantly greateramount ofefthrt in order to understandand learn the material. One of the students who had not been comine to class regularly came t o the instructor's office to pick u p & examination. When asked about his spotty attendance record in class, the student remarked that he had all of the material in hiah school. However. the erade of 74 on the exam seemed & give him quite a shock! '&ere seems to he an apathy by students toward reviewina material so that a solid f&nd&n can be laid. In conjunction with this, students seem to resist learning something new if they think it is remotely covered hy something they already know. We constantly warn students of this apathy as manifested by hypothesis 1. We have restructured our syllabus so that we introduce "chemistry" earlier. Topics such as formula writing and ionic equations are introduced as early as possible. ~
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The student will, we hope, realize that hisher innate mathematical ability will not insure success and that a significant amount of effort must be expended in the realm of memory work. Hypothesis 2 states that the amount of work carried out by the student in class and outside of class is inuersely proportional to the effort and intensity of the instructor. I t is our experience with students that the more we do for them, the less they do for themselves. An instructor recently tried giving out skeleton notes to be filled in during the lecture. The idea was t o give students more listening and participating time during class. The result was, however, a decidedly more relaxed attitude on the part of the students as manifested by students folding arms, spreading their feet out, and chatting. Upon looking at these skeleton note sheets, the instructor found that in many cases no additional information had been added. Althoueh the students liked these handouts and praised them in their course evaluations, the instructor has lessened the freouencv of handine out this type of notes. I t is imperative that'the student stud; hisfher notes, write out or verbalize concepts, and work problems on hisher own. We as instructors tend t o work many problems, and, because we are experienced and organized, we make it "look easy". On one occasion a colleague tried to illustrate hypothesis 2 by bringing in a gymnast who deftly stood on his hands. The instructor pointed out to the class that the feat looked easy but was, in fact, the result of much effort and practice; problem solving in chemistry must be approached in the same way. I t is becoming increasingly clear to us that it is not how much work the instructor does but how much work the student does that is of major importance. Too manv students do not want to discuss and understand the mateiial in chemistry. They want the nitty-gritty work done for them. How many times have students come to the instructor's office without reading the text, without looking a t the notes, and requested that the instructor work the prohlems starting with number one? We must get across to the students that the instructor cannot learn for them. We have tried giving short outside reading assignments on descriptive material that the student is tested on but is not discussed in class. We have tried handing out a select number of problems t o the students and have informed them that one or more of these same nroblems will annear on the next test; with this incentive, we hope, the stud& will work them all. These ~edaeoaicalideas, as well as others. are attempts to increase &student's 'effort and to make the student more responsible for learnina. Hypothesis 3 states that lecture material has no application whatsoever to the general chemistrv laboratory; or, to put in another way, laboratory is not the real world d c h e m istry. We instruct our own laboratories, which generally contain about 25 students. (hing into one of these laboratories Volume 66 Number 12 December 1989
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is a humbling experience for any instructor. There is little or no carry-over from the lecture; it is as if the material were totally new. The authors have given problems on lecture quizzes and tests that the students were able to solve with a minimum of difficultv. But out those same nrohlems in a laboratory situation, and confusion hecomes rampant. Students have collected dataonlv. toienore it totallv whendoinecalculations requiring them. Experimentally, we have seen students emntv . . their burets into maduated cylinders in order to measure the volumes invol\.ed in a titrstion; we have seen "eood students" dilute a 6 M NaOH solution to 0.2 M N ~ O adding H ~ a ~standard oxalic acid solution. In the last examnle the students saw no problem with the dilution. when questioned as t o their procedure, they asked innocently what were they supposed to dilute with. Dilution, of course, had been thoroughly covered in lecture and was reviewed in the lab manual. Students are reluctant to read the experiment prior to walking into laboratory; long, painstaking, thoughtful introductions are a waste of time. We have often been asked hv students how to proceed or how muchof achemical isneeded when theinforhation is readily available in the exoerimental write-up. Although the lahoratory may indeed be the real world,-the stud& sees it as totallv foreim. Hwothesis 3 is illustrated very well by a co~le~gue's story; throughout much of the semester he had stressed that the pH of a solution can influence the products obtained in an oxidation-reduction reaction. For example, MnOa- in an acid solution can be reduced to Mn2+,but in a basic or neutral solution it will be reduced to MnOn. Close to the end of the semester his class was titrating NazC20Aaq) with KMnOa in an acidic medium. In a pre-lab lecture he reviewed the principles and wrote the balanced equation on the blackboard. As the lab nromessed, he questioned several students as to the necessity o r t h e sulfuric acid in the reaction. The response was "I don't know." Getting frustrated the instructor's voice rose perceptively as be re-explained several more times. Finally, he approached a student, and, almost shouting, he pointed to the blackboard and said: "Pat, what is that H2S04 doing u p there?" T o which P a t indignantly replied "Don't blame me; I didn't put it there." What have we done to confront this alienation that occurs in
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the lahoratory? We have long ago given u p the investigative approach and have turned to lecture reinforcement experiments. Our experiments are highly structured; we assume nothing. We require the students to complete and write u p the experiment in the same lab period. We give post-lab quizzes and are trying pre-lab quizzes along with the pre-lab lecture. I t is here where computer-assisted instruction would be a most valuable tool in increasing the student's understanding. Hypothesis 4 can be stated simply as the less the student gives, the more the student expects. In one incident an instructor gave partial credit on a buffer preparation problem. The student found the moles of weak acid and moles of strong base initially present but proceeded not to use them in calculating the pH of the resulting buffer solution. The student armed for more credit because he had a t least a third of thLwork. It never dawned on him that he missed the whole mint of the nrohlem and that the partial credit he received was a gift! Hypothesis 4 may be minimized by telling the class an analogy such as the following: In a marathon finisher who was only one second race, the second slower, received $5,000 compared to the winner's $25,000. The monetary reward was a subjective decision of the sponsors of the race based upon their knowledge and experience. Similarlv..an instructor's exnertise nermits himher to "iudee the relative merit of a student's answer. The same reasoning may he applied to other subjective decisions such as rourse requirements and test content. Wedo not want toend this paper with the impression that we have thrown in the towel. In fact, we have increased our effort to enhance student understanding in lecture and laboratory. We have worked long and hard on our experiments and have tried to he innovative. The occasional frustration has spurred us forward to try and improve student-teacher attitudes. We only hope that this paper will, in some way, make other veteran teachers realize that they are not alone.
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Acknowledgment
The authors wish to thank Gerald Scheppers of the Universitv of Wisconsin-Platteville chemistw for . deoartment . his editorial advice.
