The instructional level, a measure of optimal instructional challenge, addresses the amount of review material interspersed with new. The current study further attempted to identify the instructional level for drill tasks by teaching sight-words to five fourth grade students with reading disabilities and documented attention difficulties. Four different drill ratios, 0% known, 50% known, 83% known, and 90% known, were used with a 1-week retention interval and both recall and on-task behavior being the dependent variables. Results suggested that the 90% known condition led to the highest percentage of on-task behavior and the highest retention, but required much more time to complete. Limitations and implications for future research are included. (Contains 2 figures.)