Symbiosis is a fascinating and diverse phenomenon. The study of symbiosis is important to understanding ecology, as it helps us understand relationships between organisms and provides insight into co-evolution, mutualism, adaptation, and survival. Ecological studies are challenging to implement in K-12 classrooms because they often require multiple organisms (often very different in size) and complex environments that are difficult to replicate accurately (e.g., soil composition, temperature, pH, and humidity). These factors can make it difficult to study quantitative changes in ecosystems. We developed an inexpensive, quantitative experiment for classrooms that can be used to explore important aspects of microbial symbiosis, pathogenesis, and ecology, and that helps support more investigations in this area of education. The experiment is low-cost, designed for K-12 teachers and students, uses common materials, and teaches students about the exciting relationships among bacteria, worms, and insects.