In this unit, students will explore how plants and animals get the matter and energy they need to live and grow, how they interact in food webs, how change in one part of an ecosystem can have various effects, and how newly introduced species can sometimes become invasive. Students investigate what contributes most of the matter to plant growth. Starting with a broad list of what plants need to live and grow, students narrow down this list of water and air through a series of investigations that provide evidence for or against each potential contributor. Students explore animals’ needs for matter and energy. By analyzing weight and food intake data, and observing energy transfer from food items, students build the case that animals get both matter and energy by consuming food.