Introduction Schema-based instruction has been shown to improve diagnostic performance and reduce cognitive load. However, to date, this has only been studied in controlled research settings. More distractions in classrooms may limit generalizability to real-world settings. We evaluated whether schema-based instruction would maintain its effects on cognitive load optimization and performance in a classroom.

Methods Focused on the approach of interpreting cardiac auscultation findings, 101 first-year medical students at Western University were randomized to receive a traditional (n = 48) or a schema-based lecture (n = 53). Students completed four written questions to test diagnostic performance and a cognitive load assessment at the end of the lecture. Diagnostic performance and cognitive load were compared with independent t-tests.

Results Schema-based instruction was associated with increased diagnostic performance on written questions (64 ± 22 % vs 44 ± 25 % p < 0.001) and reduced intrinsic cognitive load (mean difference = 15 %, standard error 3 %, p < 0.001). There was no significant difference in reported extraneous (p = 0.36) or germane (p = 0.42) cognitive load.

Conclusions Our results demonstrate that schema-based instruction can be used to reduce intrinsic load and improve diagnostic performance in a real-world classroom setting. The results would be strengthened by replication across other locations and topics.