,
,
Grading a Large Organic Laboratory Course Marjorie Kandel State University of New York at Stony Brook, Stony Brook, NY 11794 Problems and Goals Because the results students obtain in the organic laboratury course are generally nonmathematiral, grading can be a problem. The followina kinds of situations led to changes in our method of assigning grades: A student who is all thumhs in lab does well on the final exam
and gets an A in the course. The sense of justice of all concerned staff is violated. A student is argumentative about a low grade assigned for techniqueor for a report. While the instructor is confidentthat the grade is fair, there are no quantitative measurements hehind it. A teaching assistant has assigned technique or report ~ a d e * students m his or her section. The insrruetor is not c~mpletely confident that the TA has the experience or judgment 11, do so
.-...,.
The instructors have worked several semestersto develop a fine experiment. Unfortunately, the experiment has to be replaced because all reports are becoming the same due to student familiarity with past grading. The above problems can he restated in terms of grading goals: We want to stress the right things. In the laboratory, these are the ability of the students to solve problems (both predicted and unexpected) as they arise; to perform manipulations with reasonable dexterity; to make observations and keep adequate records of them; and to interpret results. The ability to learn facts or solve dry-lab problems is relevant hut not enough. We want to avoid spending an inordinate amount of time explaining or arguing about bow grades were assigned. We wantto avoid dependenceon thevaried competencies of our teaching assistants and on their values that might conflict with
. .
"llrs.
We want to devote more of our energies to the course content and Less to monitoring collaboration among students, present and past.
Regardless of the system, many of our students will be strongly motivated to try for good grades. The best system has the grades fall out naturally when students are "doing the right things". If they see the grading as sensible, not arbitrarv. students are encouraeed to place their own emphasis on what the instructor thynks is h o s t important. Our grading system is now structured so that we are directly evaluating what we want the students to he learning. Emphasis is placed on the individual's data and results. ~ e c i u s of e the way grades are determined, information from the network of presentlpast students is not especially useful. Each assignment is graded by one teaching assistant for the entire course, and the difficulty of the assignment is matched to the TA's competence. This past semester, about 200 students were graded with a total of 1-15hours spent on each. Let us assume that we have met our last three goals to the satisfaction of the instructors and manv of the students. As experienced laboratory supervisors, we know that students exoect hieh erades in our courses because thev have done the wdrk (that is, come to lab and followed the procedures in the manual). We know we cannot satisfv them all, but on course evaluations a majority rate our grading fair, if sometimes "picky". Let us turn our attention to the mechanism of achieving our first goal, which relates grading to learning.
782
Journal of Chemical Education
T o measure the solving of lab problems and the performance of manipulations, we gradeproducts. To measure the demee of alertness in lab and the faithfulness of record keeping, we grade notebooks. T o measure the knowledge acquired and applied to results, we grade exams and a final report. To acc&nt for the immeasirahles that may he apparent to an observer and for superficial accidents, we have a small technique grade and an exceptions policy. Products (30% of the grade) These are graded for quality and quantity, the first being emphasized. We divide the quality part into appearance, melting point if solid, and gas chromatograph if liquid. The general procedure is for the grader to group samples by quality of appearance and then process the top group by taking the MP or the GC. We do not rely on student-supd i e d data. Samoles shown to he oure receive full credit: ihose not processed or shown to b e impure receive part credit. We can detect doctored samples, and the students realize this. We divide the quantity part into a weight check for accuracy and a percent yield compared to that obtained by other &dents. o f course, the amount of limiting reagent is controlled to prevent yield inflation. Considered in the category of product grades and evaluated in traditional ways are the student's thin-layer chromatography plates, infrared spectra, and gas chromatographs. Students rarely complain about a product grade, because it is not subiective. Our novice eraders are eiven these assignments, which are quite time consuming. There is a payoff in direct information about a student's laboratorv accomplishment. To compensate for the time spent on products, we have streamlined how we evaluate written work.
-
Notebooks (30% of the grade) Our method of evaluating notebooks is described in another paper (1).Briefly, we are concerned with having the students write as they work in lab and with having the desired contents included. We keeo track of when the notebook was written by requiringcarbk copies of all pages to be turned in before the end of the period. We check the contents via several short notehood exams with questions on procedure, data, observations, and those conclusions that must be made on the spot. T o answer the questions, students consult notebooks; to check, graders consult carbon pages. The complaints we receive are the same in kind as those we used to have when we graded notebooks in traditional wavs. However. the fact that an exam format is used eives theoperation akhority. The number of complaints is faFless than in the past, and the amount of time spent in grading is a fraction of that previously. Most important, we feel we are eettine an evaluation of this asoect of the student's work Lninflienced by neatness or sheer mass. Exams and the Flnal Report (40% of the grade) We distineuish between the notebook exams discussed above and tce theorylpractice exams, which are also open hook. Manvofthe auestions call for the students to interpret typical data, some-of which are their own. Thus, we have dispensed with most lab reports, with their attendant prob-
.
lems of wordiness and collaboration. However, we retain the report on the qualitative analysis of an unknown compound, which is the final experiment. Students are given a brief outline for guidance and a page limit that makes them select what to include. Part of the grade is based on the quality of presentation, including grammar, spelling, and editing. Grading of the final report is time consuming, requires mature judgment, and is the assignment of our most skilled TA's. We feel that our students gain valuable writing experience, and the effort on our part is justified from that point of view alone. Technlaue and Exce~tlons
We have tried various methods of making a discretionary adjustment of the final gmde, hased on TA lab observations. ~ L c a u s ethere is so much variation in this factor and some doubt as to its reliability (2), we have settled on having i t count for 2% of the made but onlv in borderline cases. T o deal with pr&lems ranging from spilled products to missed exams. we have an exce~tions~ v allows each * o l i"c that student to ask for special consideration in one instance only. We are thus able to he flexible in the face of a potential disaster. We set a time limit for exception requests to prevent their end-of-semester accumulation.
Achievement of Our First Goal
Have we been able to change our emphasis in grading to evaluate those skills peculiar to a lab course? The author has experience with thousands of students over 15 years. Repeatedly, in small sections where her impression of the students' performance can be compared with grades assigned by the above methods, there is a high correlation. There have been some discrepancies, but these are not offensive-perhaps the grading system reveals strengths that would he missed in a shy, independent worker. Finally, that student who does well on tests will continue to do well in the theory/ practice exam part of the course but now must demonstrate other skills to get the A. Acknowledgment
The work of Miles Pickering ( 2 4 ) has inspired us in our search for workable eradine methods with the eoal of teaching what is best learned through the laboratory. Literature Cited 1. Ksndel. M. J. Cham. Educ. 1986.63.706,
2. 3. 4. 5. 6.
Pickering,M.:KolLa,O. J. C h m ~ E d u el916.53.313315. . Piekering, M. J. Chem.Educ. 1984.61.861-863. Piekering,M.J Chem Educ. 1978,55,511612. Pickering,M.;Goldsfoin,S.L. J.Cham.Edue. 1971,54, 31b317. Pickering, M.; Monts, D.L. J. Coll. Sci. Teach. 1979.8(4), 23G239.
Volume 65
Number 9
September 1988
783
