This report presents the procedure, results and conclusions of a study designed to test the hypothesis that there would be no difference in the number of acceptable laboratory reports submitted by students in a ninth-grade science course under a schedule of continuous reinforcement where the teacher graded every report, as compared to the number submitted under a 25 percent variable-ratio partial reinforcement schedule where the teacher graded only one out of every four reports submitted by students. A 2 x 2 quasi-experimental design was used with two groups of 48 students during an 18 week period. Results indicated no significant differences between the two groups. Several limitations in interpretations of the results and the implications of the findings for classroom procedures were discussed. Bibliography. (LC)