The current study investigated the discreet task completion hypothesis presented by C. H. Skinner (2002) by investigating how the rate of interspersing affects performance on and preferences for academic assignments. Specifically, 70 sixth-, seventh-, and eighth-grade students were presented with four assignment pairs of multiplication problems. Each pair consisted of a control assignment (i.e., no interspersing) and an experimental assignment (i.e., interspersing) that interspersed at one of four rates (i.e., no interspersing, every other problem, every third problem, or every fifth problem). After working on each assignment pair, assignment acceptability was measured. Results indicated that although students completed the same number of target problems with the same level of accuracy within assignment pairs, total problem completion rates were affected by the rate of interspersing. In addition, students' acceptability of the assignments was strongly related to the discrepancy in total problems completed across assignment types within assignment pairs. Discussion focuses on predicting students' preferences for academic assignments, implications for practitioners, and directions for future research. (C) 2007 Wiley Periodicals, Inc.