Motivational Impact of Bonus System Grading In the design of grading systems it is important to distinguish clearly between situations where the primary intent is to establish a quality scale and those in which the main aim is to offer a carrot to get students to complete a specific piece of work. The study described here eomuares two rradine.systems for their motivational impact on the students, as assessed by the completeness . of return of homework assignments. In 1977 Piekering and Goldstein' described an experimental grading system for lab courses. As a part of this system, open-book exams (two lab practieals and a lab written) were used to rank order students, and lab reports became, in effect, homework. Lab reports were checked, errors marked, and students were then expected to correct all major errors, attaching an appendix if necessary. In this system, failure to turn in even one report or corrected report results in the loss of credit for all reports. In the Princeton general chemistry program we award the student in all-or-none "bonus" for satisfactory completion of the reports and corrections. This honus consists of 5%of the course grade. (The general chemistry lab is combined with the lecture for grading purposes a t Princeton.) I n contrast, lecture problem sets are graded piecemeal by the teaching assistants, but total 20% of the course grade. The number of students in our course who did not complete all the work assigned is compared below. In the problem set category we have only counted sets as "omitted" if no work a t all was turned in. We have also tabulated the cases of lab bonus loss by cause. Since each student is exposed to both motivators simultaneously, they act as their own control group. Total % losing bonus Major eorreetlons not submitted One or more reports were not submitted
5.0% 2.5% 2.5%
Total % not turning in problem sets Failed to turn in a t least one problem set Failed to turn in more than one problem set
10.6% 10.6% 5.3%
The percentage of students who failed to turn in one or more problem sets is significantly larger than those failing to meet the requirements for the bonus (x' = 4 . 3 7 7 , ~= 0.05).The "honus" is therefore a much more efficient motivator than piecemealgrading. This is not verv surorisine. -. reallv. ..considerine the success of Christmas Clubs. insurance installment sales.. etc... which use the same motivational principle. The reason for the success isihat a student who does not complete one problem set loses at most one seventh of the 20% of the credit assigned to all seven problem sets (2.86%),while a student who fails to turn in a lab report loses 5% of the course grade. Essentially, the same 5% of the course grade is used to motivate each report. The bonus enjoys excellent student acceptance. We have never yet had a student who decided to sacrifice the bonus entirely by doing no work in the lab. Usually the student does the first report, and then the remaining reports are done to protect that investment of time. The bonus is simpler to administer also. There are no section corrections, and the criterion does not depend on TA's. Most students either obviously deserve the bonus or are obviously hopelessly out of range. The number of borderline cases is very small, whieh saves time and ulcer-generating areuments for the orofessor in eharee of the lab. Also. almost no students ever aooeal their bonus made. It seems to;s that thk idea of "all-or-no";" credit can read& be extended to a number of other situationskhere maximum motivation for a minimum amount of credit is required, and where the creation of a quality scale is not a prime concern.
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'Pickwing, M., and Goldstein, S. L., J. CHEM. EDUC., 54,315 (1977). %Authorto whom correspondence should be addressed.
David L. Monts Miles PickeringZ Princeton University Princeton, NJ 08544
Volume 58, Number 1, January 1981 1 43
