A procedure known as mathematics interspersing provides students with additional opportunities (i.e., brief math problems) to complete math problems within an assignment by embedding brief additional problems among longer target problems.Previous research (e.g., Cates & Dalenberg, 2005) found that the more problems completed on an assignment with interspersing, the higher the likelihood the student chooses that assignment relative to an assignment without interspersing. Some students, however, choose assignments without interspersing.The purpose of this investigation was to focus on students who do not choose assignments (i.e., non-choosers) with interspersing relative to assignments without interspersing and replicate and extend previous research (e.g., Cates & Dalenberg, 2005) by manipulating relative problem completion rates at various fixed ratios (FR) (i.e., 0:1 [no interspersing relative to every longer problem], 1:3 [short problem following every three longer problems], and 2:1 [two short problems prior to every longer problem]).Further, students were given a choice between assignments with and without interspersing to determine choice consistency and whether a richer schedule of interspersing (i.e., 2:1) could influence students to choose assignment with interspersing.Participant information regarding reinforcement histories for completing mathematics assignments was also gathered.Results showed that participants, overall, chose and completed more problems on assignments with interspersing relative to those without interspersing. Choice remained consistent for choosers, but the richest interspersing ratio caused non-choosers to choose assignments with interspersing. Non-choosers completed more total problems on assignments with interspersing for both the 1:3 and 2:1 assignment pairs. Relative problem completion rates increased for choosers and non-choosers as interspersing ratios increased. Regarding past reinforcement history, participants reported receiving positive reinforcement most often after completing math assignments in the past. The discussion focuses on potential explanations and interpretations of results, and current limitations, future research endeavors, and applied functions of interspersing are also discussed.