Teaching Exponential and Logistic Growth in a Variety of Classroom and Laboratory Settings

Abstract

Ecology and conservation biology contain numerous examples of populations growing without bounds or shrinking towards extinction. For these populations, the change in the number of individuals generally follows an exponential curve. On the other hand, limited resources may keep population numbers in check and help maintain the population at the environment's carrying capacity. These density-dependent constraints on population growth can be described by the logistic growth equation. The logistic growth equation provides a clear extension of the density-independent process described by exponential growth. In general, exponential growth and decline along with logistic growth can be conceptually challenging for students when presented in a traditional lecture setting. Establishing a solid understanding of exponential and logistic growth, core concepts in population and community ecology, provides a foundation on which students can build on in future studies. The module described here, employed in either a laboratory or classroom setting is designed to actively engage students in building their understanding of exponential and logistic processes. The module includes components that address a variety of learning styles (visual and tactile, for example). The module consists of pre-module assessments of students’ prior knowledge, three short “chalk talks” on exponential and logistic growth, the activities, and post-module assessments.