Retrieval practice and spacing in an engineering mathematics classroom: Do the effects add up?

Mathematics learning is critical in STEM degrees. In engineering specifically, advanced courses depend on the derivation and application of higher-order equations, and long-term retention of early mathematical concepts is mandatory. Cognitive science research has shown that learning and memory can be improved with simple manipulations of material retrieval. One major finding has been that increasing retrieval practice improves material retention more than restudying the material (the retrieval-practice effect). Independently, spacing retrieval over time is known to improve material retention (the spacing effect). To date, no research has studied these two effects in conjunction. This NSF-funded study investigated retrieval practice and spacing in an engineering mathematics classroom. Separately, increasing retrieval practice and increasing spacing both improved final exam performance. In combination, they produced the greatest learning gains.