Teaching experimental design in a sophomore-level lab class
Air and Water lecture and lab is a required second-year course in our environmental science undergraduate degree. The course is an introductory environmental chemistry course. To revamp the labs, we asked, "What do students need to learn between their first-year introductory course and their fourth-year capstone, Environmental Monitoring? How do they apply knowledge from basic science (e.g., chemistry, statistics) to environmental research?" A missing component was experimental design. The Air and Water labs included both guided laboratory work and a group research project, which we revamped to emphasize experimental design.
To focus on experimental design, we constrained some of the project choices and adjusted the labs leading up to the project. We only allowed students to use instrumentation and techniques which we had previously introduced. Accordingly, student projects looked at water quality or particulate concentrations in air. Students selected their own field sites and tests. Our goal was for students to generate enough data to conduct a t-test. We updated the labs preceding the project by adding instrumental analysis techniques, such as replication and matrix spikes. We also created new sections in the lab manual on statistics and quality assurance and quality control.
Students presented their final projects in a poster session attended by peers and faculty. They gained experience in original data collection and analysis, group work and collaboration, and formal presentation of results. Students reflected that the projects were their favorite part of the course. They enjoyed the open-ended, hands-on nature of the project, and felt they had the skills needed to perform their analyses, but were challenged when it came to sampling design and statistical analyses. Based on this information, we recommended a revision to the environmental science curriculum, so that students will take statistics prior to these labs. That change will start in academic year 2021-2022.
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