Effective grain-size of mastery-style online homework levels

Mastery-style online homework is used in a preparatory physics course at the University of Illinois in Champaign-Urbana. Managing student frustration and making homework content achievable is a priority. In a level that historically has been difficult for students to master, content was broken into two smaller mastery levels for half of the students, with the original level given to the other half. Students performed similarly on follow-up assessments and spent similar amounts of time on the homework and assessments, but significantly more students were able to master the content when they were split into two smaller units. Further, students who saw split levels spent significantly less time re-doing problems that they had previously mastered