Student Commitment to Self-evaluation

BAYARDO B TORRES

Departamento de Bioquimica Instituto de Quirnica Universidade de S?to Paulo Sdo Paulo Brasil

Introduction Evaluation is one of the most potent forces affecting education and its influence on students' behaviour has been widely investigated. 1 Nevertheless, among cur- riculum components, evaluation is probably that which has undergone the greatest distortions. Its potential instructional wealth is almost always under-utilized, the spectrum of its influence on the educational process being reduced to its role as an instrument of measurement. Thus, R H Thomas: 2 "The most obvious thing to say against the conventional method of examining as an aid to learning is that it disproportionately rewards the ability to memorize, a criticism that is not invalidated by the fact that the ability to recall what one knows when it is needed is extremely important."

Although this restriction may be attenuated by the formulation of high-level questions or by open-book examinations, very little attention has been devoted to remedial measures for those students who performed poorly. The term evaluation is often employed as though it were a synonym of examination, a generic term that encompasses oral, practical or, more frequently, written examinations given during and at the end of courses, and which usually constitute the main instrument for measur- ing students' achievement. In the conventional procedure, students write out the answers to questions formulated by the teacher who then judges their achievement and assigns a grade based on this judgement. The student is often not even made aware of what was considered satisfactory or wanting in his/her examination. To quote Tyler: 3 "This practice of describing a student's performance by assign- ing a single score greatly over-simplifies the complexity of the student's behavior and of the learning process". This method of educational evaluation, in which instructional and formative components are virtually eliminated, ascribes to the teacher exclusive competence and responsibility for judgement of the student's achievement. Discussion (should there be any) following "the pro- nouncing of the sentence", is strictly limited to petitions on the part of the student; the teacher may defer to the argumentation or not according to his/her own personal criteria since the final deciding power lies exclusively in his/her hands. Thus, even in courses in which student participation is encouraged or even demanded in other activities, the student is excluded from the process of judgement. Any attempts at correcting errors that led to poor performance (errors which will probably make assimilation of subsequent content difficult) are also excluded in the traditional procedure.

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To make evaluation an integral part of the learning process requires an in-depth alteration of the manner in which this process is seen by students and teachers. One attempt towards alteration which shows some promise is that of sharing the responsibility of evaluation with the students themselves, committing them to judgement of their own learning. The intention of this article is to describe a procedure of this type that is being used in an introductory biochemistry course.

Procedure The method has been in use since 1984 and consists of double correction of examinations: apart from the teacher's corrections, students also correct their own exams. Such exams (one examination upon conclusion of each third of the course) constitute the only instrument for attributing grades in an introductory biochemistry course at the University of Silo Paulo. The total class load is 236 hours (4 hours/day, 4 days/week), the number of students varies from 70 to 100, and the course is given by four teachers. Data presented in this article refer to the examinations of one complete school year.

The number of questions on each exam varies from 5 to 11, and each question is made up of several sub-items and situated (at the very least) at the Application level of Bloom's Taxonomy. 4 Exams are given in the conventional manner and take an average of 3 hours to complete (there is no time limit). The next day, papers are returned to the students for the first correction. At this time, the teacher gives the complete ideal answer to each question orally. This answer will serve as a reference for correction. The teacher also formulates overall correction criteria which, when necessary, are discussed with the students and adjusted according to their suggestions. Students assign a value between 1 and 10 to each answer, and the papers are then returned to the teacher for the second correction. A previous agreement between teachers and students stipu- lates that in case of disagreement (differences greater than 1) neither of the two judgements will prevail: teacher and student discuss the question privately at which time a consensus must be reached. As the results presented will demonstrate, such cases are rare and easily solved.

Results and Discussion The results of independent corrections made by students and teachers are very similar (Table 1). Actually, teachers and students attributed the same grade to more than 75% of the questions. In the larger proportion of those cases in which evaluations differed, students gave lower grades than teachers. For the three examinations, the proportion of cases in which the student had given a lower grade than the teacher ranged from 14 to 16%, as against 8.5 to 10% of cases in which the teacher had given a lower grade. There is no significant variation in this distribution pattern for the three exams, and overall examination grades given by teachers and students show an even greater percentage of coincidence, thus demonstrating that there was no systematic attribution of higher or lower grades.

B I O C H E M I C A L EDUCATION 19(1) 1991

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Table 1. Comparison of grades given by students (S) and those given by teachers (T). The data given in the Table represent percentages on the respective totals of 348, 275, and 605 questions analyzed from the first, second, and third exams

1st Exam 2nd Exam 3rd Exam S = T 75.5 75.8 75.2 S < T 15.0 14.3 16.3

difference ~< 1 7.5 8.4 7.3 difference of 1 to 3 5.8 4.4 6.3 difference of 3 to 5 1.4 0.4 2.2 difference > 5 0.3 1.1 0.5

S > T 9.5 10.2 8.0 difference ~< 1 4.6 7.3 4.6 difference of 1 to 3 2.9 2.9 3.0 difference of 3 to 5 0.9 0.0 0.8 difference > 5 0.8 0.0 0.2

However , the most important result stemming from the procedures described in this paper cannot be expressed in quantitative terms. Students are very pleasantly surprised to learn that the main objective of the evaluation process is not judgement , but guidance. Their surprise is ob- viously derived from the well known fact that many students study with one primary goal in mind: good performance on course examinations.

When students review their examinations critically, they have an opportunity to really check out the concepts acquired and to know exactly where and why they erred. This is actually more than an opportunity, it is an obligation: for students to be able to judge whether their answers were correct or not, they must be capable of understanding precisely both the question and its answer. This is the right moment to correct any misunderstanding of the concepts involved in the question. Having to explain these concepts to those who gave the wrong answers inverts, at least momentarily, the teacher 's natural tendency to pay more attention to the brighter students. Many cases of differences between grades given by the teacher and those given by the student can be attributed to the difficulty many students find in discern- ing what is essential and what is merely trivial. Thus, students sometimes assign too great a value to errors that the teacher may judge of minor importance, and vice versa. In any case, discussion of the fundamental concepts involved comes to constitute a short revision of the subject matter brought up by that question. Finally, one arrives at the situation in which those students who failed to answer the question correctly do no simply accept that their answer is incorrect, but they themselves judge it to be incorrect. This fact engenders a fundamental difference in attitude and tends to promote a substantial change in the students' behavior.

Actually, what one achieves is a total lack of evaluation- derived friction between teachers and students. After the first examination there are clear changes in the whole

B I O C H E M I C A L E D U C A T I O N 19(1) 1991

atmosphere of the course. Student attitudes change from neutrality or superficial cordiality, to trust and team spirit. The lack of concern about grades demonstrated by students during discussion of exams is remarkable: their attention, probably a reflection of the teacher's attitude, is totally focused on understanding the concepts involved. Another benefit that has been observed is the awakening of an awareness of the need for logical and well-organized exposition. A lot of self-criticism goes on when the students themselves find hard-to-judge ambiguities and/or contradictions on their own texts. Results of this type more than compensate the time required for this cor- rection process (never less than two hours per exami- nation).

Student receptivity and approval of the procedures described here are confirmed by course-evaluation ques- tionnaires: 100% of the students surveyed emphatically endorse (5 on a scale of 1 to 5) maintenance of the method for the next courses.

Naturally, this form of evaluation ties in with the whole methodological approach used in the course, which emphasizes student initiative and active participation. Even so, for those who seek a more productive form of evaluating their students, this procedure certainly does offer several advantages.

A p p e n d i x

Some sample questions, with summary answers to Q1 and Q2

Q u e s t i o n 1

The table shows data for an enzyme-catalyzed reaction with or without the addition of a reversible inhibitor I. Plan the additions to tube 5 in such a way that measure- ment of the initial rate of the reaction indicates the kind of inhibition produced by inhibitor I.

Enzyme Substrate I Initial rate Tube (txg) (mM) (pog) (nmoles product/min)

1 1 1 - - 18 2 1 2 - - 20 3 1 3 - - 20 4 1 3 1 15 5

A n s w e r Tube 5 should contain 1 I~g of enzyme, 1 I~g of inhibitor I and a substrate concentration greater than 2 mM. If its initial rate is 15 nmoles of product/min then I is a non- competitive inhibitor; if the initial rate is greater than 15, I is a competitive inhibitor. 20 nmoles of product/min is Vmax under the assay conditions (data from tubes 1, 2 and 3). If the rate decrease observed in tube 4 is due to the presence of a competitive inhibitor, increasing substrate concentration will favour substrate binding to enzyme thus relieving inhibition until Vmax is attained.

If the rate decrease in tube 4 is due to the presence of a noncompetitive inhibitor, then its initial rate is the maximum possible rate observed in the presence of 1 p~g I, for the substrate concentration in this tube is already saturating (as in tube 3) and increasing the substrate concentration will not increase initial rate.

Question 2 Suppose you have a mitochondrial suspension and methods for measuring oxygen uptake and ATP synthesis. using succinate and malate as substrates, which pro- cedures would you use to identify the contents of 4 vials that have lost their labels? It is known that each vial contains one of the following kinds of compounds: cytochrome oxidase inhibitor, uncoupler of oxidative phosphorylation, NADH dehydrogenase inhibitor and oxidative phosphorylation inhibitor.

Answer Measure oxygen uptake and ATP production with suc- cinate and malate as substrates (control). Similar measurements should be done with the addition of samples from each of the unlabelled vials. Decrease of ATP synthesis associated with increasing 02 uptake would indicate the presence of the uncoupler. Tests with the 3 other samples should have the same result, ie inhibition of both ATP synthesis and 02 uptake, when malate is used as substrate. Now measure 02 uptake and ATP pro- duction in the presence both of samples from each unidentified vial and the uncoupler: 02 uptake will be restored only with the sample from the oxidative phos- phorylation inhibitor, which is thus identified. Distinction between cytochrome oxidase and NADH dehydrogenase inhibitors could be made because both will inhibit 02 uptake and ATP synthesis if malate is the substrate but only cytochrome oxidase inhibitor will be effective when succinate is the substrate.

Question 3 The Table presents caloric intake (in Kcal/day) from a normal diet and from a proposed diet A.

Normal A

Carbohydrate 1600 I60 Lipid 900 2340 Protein 400 400

From a consideration of allosteric and hormonal regu- lation of metabolism, what could be predicted about: (a) the metabolism of triacylglycerol in adipose tissue, (b) the nitrogen balance and metabolic destination of aminoacids, (c) the fat acid metabolism in liver, (d) the metabolism of hepatic glycogen, and (e) the activity of pentose phosphate pathway in adipose tissue in persons consuming diet A? Is diet A recommendable?

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Question 4 What are the metabolic similarities and differences be- tween diabetes mellitus and starvation?

References 1 Crooks, T J (1989) 'The Impact of Classroom Evaluation Practices on Students', Review of Educational Research 56(4), 439-481

2Thomas, R H (1976) 'The Necessity of Examinations and their Reform', Studies in Higher Education 1(1), 23-27

3Tyler, R W (1986) 'Changing Concepts of Educational Evaluation', International Journal of Educational Research 10(1), 11-31

4Bloom, B S (editor) (1956) 'Taxonomy of Educational Objectives: Book I - - Cognitive Domain', Longman, London

Writing Exercises and the Biochemical Literature in the First Undergraduate Biochemistry Course

C LARRY BERING

Department of Chemistry Clarion University of Pennsylvania Clarion, PA 16214, USA

Introduction Two ancillary goals of a first undergraduate course in biochemistry are the development of written communi- cation skills and an introduction to the literature of biochemistry. Both goals are often met by the assignment of a term paper on a specific topic. This not only requires students to put ideas and concepts into an organized and readable format, but to explore a topic beyond the level of the textbook. But for many undergraduate students, their only exposure to the biochemical literature is the list of recommended reading at the end of each chapter, or the instructor's own list of required or recommended reading. Even with a paper in hand, they are not experienced in how to read a paper from the primary literature. One recent textbook includes a section on the biochemical literature, including a discussion on how to (and how not to) read a research article)

Weaknesses of Term Papers The term paper suffers from several weaknesses as a teaching tool. First, the paper is a single exercise, usually due near the end of the term. Corrected papers, if they are returned, are received late by the student. Although conscientious graders will detail errors and make suggestions for a stronger paper, it may be several semesters before students are required to undertake a similar exercise again. In large courses, papers might not be assigned due to the volume of grading that would be required. Second, students must choose, or are assigned a single topic, and must research the topic. Typical topics may seem very specialized to the student, but are very broad to an investigator. Imagine a student writing a paper on serine proteases. If he or she is familiar with Biological Abstracts, Chemical Abstracts, or has access to on-line search tools such as DIALOG, he/she would quickly be overwhelmed by the volume of literature. Even

B I O C H E M I C A L EDUCATION 19(1) 1991