Sustainable Polymers: Plastics of the Future for a Green, Clean World, Grades 3-5This is a 4 H STEM Curriculum for Grades 3 5 (8 to 12 year olds). The themes of these modules touch on the prevalence and impact of plastics in everyday life. Plastics are versatile materials that come in different shapes, sizes, and exhibit different material properties. Scientist and engineers are working on new ways to create, use, and recycle plastics, so we can use plastics for their many advantages and lessen their effects on our environment.