Students investigate decomposers and the role of decomposers in maintaining the flow of nutrients in an environment. Students also learn how engineers use decomposers to help clean up wastes in a process known as bioremediation. This lesson concludes a series of six lessons in which students use their growing understanding of various environments and the engineering design process, to design and create their own model biodome ecosystems.

Students design and conduct experiments to determine what environmental factors favor decomposition by soil microbes. They use chunks of carrots for the materials to be decomposed, and their experiments are carried out in plastic bags filled with dirt. Every few days students remove the carrots from the dirt and weigh them. Depending on the experimental conditions, after a few weeks most of the carrots will have decomposed completely.

Scientists at the University of North Carolina in Chapel Hill are studying how microbes in the soil, like bacteria and fungi, interact with a plant in ways that make the plant grow better. Someday, this knowledge may be used to increase crop production for an expanding population.

Students gain an understanding of the parts of a plant, plant types and how they produce their own food from sunlight through photosynthesis. They also learn about transpiration, the process by which plants release moisture to the atmosphere. With this understanding, students test the effects of photosynthesis and transpiration by growing a plant from seed. They learn how plants play an important part in maintaining a balanced environment in which the living organisms of the Earth survive. This lesson is part of a series of six lessons in which students use their evolving understanding of various environments and the engineering design process, to design and create their own model biodome ecosystems.