Abstract
Objective. To describe an evidence-based instructional design to improve performance and foster retention of pharmacy students' calculation skills longitudinally across the curriculum. Methods. Gagne's nine events of instructional design were employed in a longitudinal pharmacy calculations curriculum. Mean pharmacy calculation examination scores from four courses spanning the didactic curriculum for four different academic years (before and after the redesign) were compared. Results. Students demonstrated more stable outcomes with consistently higher means after the redesign, which may indicate improved retention. Additionally, the post-redesign classes have experienced fewer failures (score of <80%). Conclusion. Using an instructional design model to optimize immediate instructional outcomes is an effective method of enhancing retention of calculation skills over time.