This science unit was taught to a fifth-grade class. The students have experienced previous instruction on matter and the four different spheres. In this unit, students gain the knowledge of what it takes to sustain an environment, the flow of energy, and suitable living conditions for biotic and abiotic organisms. The goal of this unit is for students to understand the relationships that take place in a healthy ecosystem. Using a plastic bottle, the students build a model that represents their own ecosystem. By creating these models, the students observe the specifics on what makes an ecosystem healthy versus unhealthy.