PS 10-85
Reduced variance in post-test scores is an important student learning outcome: Lessons from an introductory soils course experiment
Recent reports have celebrated the joys of teaching soil science (e.g., Hartemink et al. 2014). These reports frequently note the importance of soils literacy amidst the challenges of providing food, fiber, and fuel for a growing global population. They also call for a critical evaluation of how best to teach soils. Unfortunately, some teaching strategies lack robust empirical support. In our view, there are too few case studies where students have been randomly assigned to a pedagogic intervention, and student learning outcomes measured before and after that intervention. Here we report on an experiment performed as part of the laboratory component of an introductory soils course to explore the effects of peer instruction on student learning outcomes.
Results/Conclusions
Two grant-funded instructional interventions (pilot, experimental) were conducted in Fall 2013 as part of a large-enrollment (~180 students) sophomore-level soils course at a large land-grant institution. Students were randomly assigned to either control or treatment groups, and members of both groups completed pre- and post-tests. Control subjects followed standard laboratory procedures whereas treatment subjects were responsible for teaching the subject matter and procedures to their peers. Post-test scores for both the pilot and experimental studies were significantly higher than pre-test scores (p<0.05), both for control and treatment groups. This implies the standard laboratory procedure improved student learning. Gains (post-test minus pre-test scores), however, were ~20% greater for treatment groups, suggesting a greater learning outcome return on the minimal additional time investment (~10 minutes within a 110-minute laboratory session). We also found that the post-test score variances for treatment—but not control—groups were greatly reduced: interquartile ranges decreased by ~60%. This could be an overlooked learning outcome benefit if one of the essential elements of effective teaching is addressing student misconceptions. This research provides a template for rapid and effective education interventions that promote improved learning outcomes.