Although the pedagogical benefits of inquiry-based, hands-on approaches to learning are widely known, the widespread use of such teaching strategies has been slow to develop. This is especially true at the high school level where teachers have to cope with large class sizes and limited class time. Model experimental systems have played a key role in the development of ecological concepts, and they may also provide a practical mechanism for wider implementation of inquiry-based strategies in the high school classroom. Here we outline our efforts to develop a model system, abstracted from pond food webs, suitable for conducting ecological experiments in the classroom. Our system includes the aquatic gastropod Helisoma trivolvis, the crayfish Orconectes virilis, and senescent red maple (Acer rubrum) leaves. The organisms are common, readily available, and easy to care for in the classroom environment. In addition, these organisms are part of the student’s local environment and thus hold special value in that they help the students develop a stronger sense of place. A broad range of questions can be addressed with this system, including topical issues in behavioral ecology, trophic ecology, and carbon cycling. Here we outline one example exercise recently conducted in Brady’s high school classroom.
Results/Conclusions
The exercise began with a simple engagement activity in which students compared microcosms that contained six snails and 1 g of red maple leaves alone or in combination with one crayfish. From these observations the students generated a list of questions (e.g., “Does H. trivolvis avoid O. virilis?”, “Does H. trivolvis eat leaves?”). From these questions we then developed a series of experimental tests. In the first experiment the students investigated the ability of H. trivolvis to detect the presence of O. virilis using chemical cues. In the second experiment the students investigated whether H. trivolvis processes leaf material, and in the third experiment students investigated how the presence of O. virilis affects the rate at which H. trivolvis process leaves. Each experiment yielded clear results, and the role that the students played in experimental design and data analysis increased with each successive experiment. Experiences that make students active participants in their learning produce greater student interest, make abstract concepts real, and ultimately promote understanding. Perhaps most importantly, when students become engaged in the process of experimental design, set up, and analysis, the students are not just learning ecological theory but also learning the skills necessary to test it.