The current study investigated the extent to which considering instructional time and student learning rate affects academic treatment decisions. Five second-grade students with difficulties in spelling were exposed to three spelling interventions (traditional drill and practice, interspersal training, and high-p sequencing). Using an alternating treatments design, student performance was measured and graphed in two ways, cumulative learning (a measurement that does not consider the amount of instructional time) and student learning rate (a measurement that does consider instructional time). These two measurement procedures were then compared on their ability to detect differential effects of interventions on spelling mastery. Results suggested that the cumulative learning measurement did not facilitate data-based instructional decision making (i.e., did not show differentiation across conditions); however, the more sensitive measurement that accounted for instructional time (i.e., student learning rate) did. Similar results were found for maintenance data. Discussion focuses on (a) the importance of considering instructional time when making treatment decisions and recommendations, (b) implications for future practice, and (c) directions for future practice and research. (Contains 1 table and 6 figures.)