The authors have developed a lesson to investigate basic principles of ecology, more specifically niche partitioning, while using a jigsaw activity that explores galling insects' interactions with goldenrods. Not only does this lesson capture secondary students' interest and keeps them engaged in hands-on activities, the content addresses two Content Standards (of the "National Science Education Standards") for 9-12 life sciences: (1) Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years. (2) Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms. Organisms often must compete for food and resources access in natural communities in order to survive. This is true especially for insects that live on the tall goldenrod ("Solidago altissima"). Hundreds of insects have overcome resource limitations by outcompeting other herbivores and making use of the same plant in various ways. These ecological interactions take place at the level of the individual, the population, the community, and the ecosystem. In this article, the authors offer an introduction to principles of ecology, plant insect interactions, and provide a classroom activity that highlights niche partitioning by galling insects to help provide secondary science educators with a way to share and explore these interactions with their students. (Contains 9 figures.)