The branch of biology that studies ecosystems, habitats, their developments, and the equilibrium of species is called conservation biology (Soule 1986). It is important to study this balance of species within an ecosystem, where species might live for a short period of time (such as mosquitoes, the main source of food for frogs) or live for centuries (such as the Galapagos turtles). Studying ecosystems helps scientists predict issues that may be of great importance to the survival of species. In this article, the author describes a lesson plan for intermediate elementary students that uses mathematics to analyze the behavior of a simple ecosystem that has two species: rabbits (prey) and coyotes (predator). In the model that the class studies, the predators eat their prey at a constant rate. For example, a coyote will eat two rabbits each day. The rabbits reproduce according to a pattern. The number of live rabbits after the second day follows a Fibonacci sequence: The number of live rabbits on a given day is the sum of the surviving rabbits of the previous two days. The problem scenario in this ecosystem consists of determining what happens with the population of rabbits when variables change. In this classroom unit, different variables are examined: (1) the number of predators; (2) the number of rabbits on days 1 and 2; and (3) the number of rabbits on the first day the predators come in. Preparation, activities, guiding questions, and the importance of visualizing concepts are discussed. Two student activity sheets are available in an online appendix.