Seed germination as a model of developing inquiry laboratory exercises

Background/Question/Methods

Inquiry-oriented laboratories are valuable because they teach students content and process but many faculty have difficulties understanding how these laboratories can be developed. The best laboratory exercises allow students to develop their own questions and methods and then conduct the project and analyze their results. To develop such laboratories, I recommend finding a concept that is important in the context of the subject and then developing an approach for which there are multiple variables that can be manipulated and dependent variables that are easily measured. I use a simple seed germination laboratory as the first student-designed laboratory in my junior-level ecology course. This laboratory comes in the context of physiological ecology and addresses the question of how individual organisms interact with the physical environment. Although this laboratory is very simple, most of my students have never designed their own experiments and are excited about the opportunity.

Results/Conclusions

In this laboratory, students choose an ecologically relevant variable that may affect germination or early growth of a plant. Variables that can be manipulated include light, atmospheric gases, pH, salt concentration, soil type, soil compaction, and seed scarification. Variables that can be measured include time for the radicle to emerge from the seed, time for the meristem to appear above the soil, radicle or stem length after a given amount of time, or germination/non-germination. Guidelines for experimental design are presented as rubrics and include items that address manipulated and measured variables, replication, standardization of non-manipulated variables, interspersion (avoidance of pseudoreplication), statistics, ecological relevance, conclusions, experiment improvement, future studies, presentation standards, and quality of group work. I will provide a list of possible manipulated variables (derived from class brainstorming), rubrics, hints for presenting this laboratory, problems with using inquiry-oriented laboratories, and hints to solving such problems.