Interventions that match demands to ability can enhance both academic performance and behavioral performance. However, it is unknown whether the instructional match or subsequent increases in engagement with the instructional material differentially impacts learning. The current study evaluated the effect of task difficulty on on-task behavior and responding rate across two studies. In Study 1, participants were assigned easy and difficult math probes following results of curriculum-based assessment. Data were collected on digits correct per min (DCPM) and percentage of on-task behavior during a 5-min observation period. Results from Study 1 indicated that participants responded, on average, 1.16 DCPM more per session in the easy probe condition, responded more over time at faster rate than in the difficult probe condition, and were engaged significantly more in the easy probe condition. In Study 2, the same data were collected for participants completing easy probes during a truncated observation period and compared across results from in Study 1. Rate of responding in Study 2 was substantially less than in Study 1. The interaction between task difficulty and DCPM was not significant which suggests that engagement was a substantial contributor to the growth differences in Study 1.