Erika G. Offerdahl, Melody McConnell, Jeffrey Boyer

For decades, formative assessment has been identified as a high-impact instructional practice that positively affects student learning. Education reform documents such as Vision and Change: A Call to Action expressly identify frequent, ongoing formative assessment and feedback as a key instructional practice in student-centered learning environments. Historically, effect sizes between 0.4 and 0.7 have been reported for formative assessment experiments. However, more recent meta-analyses have reported much lower effect sizes. It is unclear whether the variability in reported effects is due to formative assessment as an instructional practice in and of itself, differences in how formative assessment was enacted across studies, or other mitigating factors. We propose that application of a fidelity of implementation (FOI) framework to define the critical components of formative assessment will increase the validity of future impact studies. In this Essay, we apply core principles from the FOI literature to hypothesize about the critical components of formative assessment as a high-impact instructional practice. In doing so, we begin the iterative process through which further research can develop valid and reliable measures of the FOI of formative assessment. Such measures are necessary to empirically determine when, how, and under what conditions formative assessment supports student learning.