J. A. Rondini and J. A. Feiahan Cabrini College Radnor, Pennsylvania
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II
An Ongoing Grading Technique for Laboratory Courses
Laboratory proflams which are graded independently from accompanvinr iecture courses have often presented n problem, and on oEcaiion a confrontation, between instructor and student. Unlike a strict lecture course, for which a grade is usually determined by straightforward computation of test and quiz marks, a lab course grade is indicative of many factors, some of which are not easily recognizable to the student. When a midterm or term grade arrives, the student can always remember the one 'eood' experiment where all the color changes came on schedule, the syntheses worked to 'perfection! and all the special mound glass equipment was returned undamaged. His memory is a t :loss, however, to recall a lost product, low yields, or generally poor laboratory technique and comprehension of directions. We have devised and tested an ongoing grading technique designed to apprise the student each week of his performance in the lahmatory and his relativestanding with his lab peers. and to confronthim with the immediate reasons for his successful or not-too-successful completion of a particular assignment. In this way, the student will be aware of his strengths in lab work and can concentrate on overcoming his weaknesses. The following method has been applied to grading an organic laboratory course with an approximate enrollment of 20 students, where the experiments involved a variety of synthesis methods, property tests, qualitative identification of unknowns, and quantitative results. With minor modifications, however, the method would be wellsuited for grading in other laboratory courses. The basis of the marking procedure is a scoring system (0-10) and a scoreboard (24 X 36 in.) on which each student's
weekly score is posted. (Should a synthesis require longer time, the instructor might opt for double weight for the experiment or grade separately for technique and results.) The figure illustrates a partial scoring utilizing a vertical column of grades for each student, which allows for easy recognition relative to class standing as the course progresses. Anonymity in posted results may 6e achieved by "sing student numbers (or code letters) rather than student names on the scoreboard. objectivity in the grading is accomplished by comparison of product yields and sample purity throughout the student group. Average yield might be graded as 6-7, high yield 8-9, and a yield which is much lower than the class average might rate 415. Other factors involving laboratory techniques, such as equipment setup, handling of chemicals, overall comprehension of ~ ~ directions. ~ ~ ~ .etc... are then used to raise or lower individual scores. These decisions would be made after consideration of the lab instructor's notes on his personal observations of the student's performance in the lab for that week. A rather important aspect of the system is that these adiustment factors are noted below the weekly grade for each student. A performance code lettering system (table) which indicates reasons for particular weekly grades is used for this purpose. In this way, students are not only aware of their grade for a particular experiment but are also informed immediately of why they have received a specific grade before the experiment becomes just another unrecognizable organic synthesis, buried in their notebook. To illustrate the method, let us assume that for a synthesis one student is graded ~~~
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STUDENT .-j
Laboratory Performance Code
1st week
a. high yield of prcduct b. average yield ot product (far current class group) C. poor yield of product
2nd r e e k 3rd week
d.
product discarded f. student not following rules of proper lab discipline g. careless handling of chemicals or equipment h. prcduct cloudy (indicateswater present) j. product impure k. solid product wet
4 t h week
5th r e e k 61h week
I, product of high purity m. drastic overhsating n. improper equipment set-up 0. inability of student to comprehend directions
7thveek 8 t h week 4 h weak 0th 1 e j
TOTAL SC
dirty equipment
e.
wIiI
1
10 7I 4 1 10 9 10 6 5 83 87 82 72 76 56 49 Q{
Students are identified as A. 8. C, etc. to preserve anonymity.The weekly lab grade scale varies between 0-10. Reasons influencing a particular weekly grade are indicated by small code letters (a, b, c, etc.).These are detailed in the table. Grades and reasons are entered weekly throughout the semester. 182 / Journal of Chemical Educafion
p. bestprcduct q. gocd time for completion of experiment r. average time for completion of experiment S. p ~ time r for completion of experiment t. excellent overall technique u. poor overall technique Y. misrepresentation of yield or purity w. unknown correctly identified X. unknown inconectly identified y. student not working independently 1. Student disregarded laboratory safetyregulations
The key factors influencing this grade are noted in the scoring box as a, I, and q, and refer, respectively, to high product yield (a), product of high purity, (I), and good student time (q) for the experiment. If a student performance in such a synthesis is poor and is rated
this is interpreted from the performance code (table) as representing a case where the product yield was low (c), the submitted product was cloudy due to incomplete drying of the water present (h), and that generally poor lab technique was noticed (u). For a given semester, we have allowed for ten grades. No grades are given for the preliminary experiments assigned at the beginning of the semester because it is felt that the students need time to adjust to the variety of new techniques peculiar to organic lab work, and the care needed in handling special glassware. The scoreboard does not include a grade for the lab reports or lab notebooks and a general grade for these can be added at the end of the semester, as well as the grade for a final written lab examination.
The weighting factors used by the authors in arriving a t a semester grade for an independent organic laboratory course are as follows Lab Scureboard totals = 75%of rotal gmde Lab n
