Science, technology, engineering and math (STEM) advocates commonly emphasize an interdisciplinary, authentic, project-based, and technology-based approach to learning, though the strength of prior research varies. This study examines the association between a range of classroom activities and academic performance gains in math and science. Using longitudinal data from North Carolina middle school students, estimates of the effect of classroom practice are generated. Indicators for listening and taking notes and using computers, calculators, or other machines in math class were most positively correlated with student gains in math achievement. Similarly, indicators for completing a science experiment or project and listening to the teacher explain something about science showed positive correlations with gains on the eighth-grade science exam. These relationships held when limiting the analysis to underrepresented racial minorities.