As I teach 5th and 6th grade I chose to do 5-PS2-1
SEP's: Model Making– Ecosystem is a great chance for students to take the information they understand and create, gain new knowledge, improve, and continue to revise their models. Along with the model making process, I think that food webs allow you to connect many themes or ecosystems to draw in on students specific interests and preferences. These can be done digitally, drawing, or a physical model and regardless of the type of model, as an instructor we gain useful information on how well our students are able to communicate their understanding.
DCI's: Cycling of matter is a difficult concept for students and in my personal opinion the cycling of matter through an ecosystem doesn't really come into full effect until you connect the idea of plant and animal systems and cells. When you are able to connect the idea that cells have basic requirements and they take in nutrients and get rid of waste, then you can tie this idea back to a food web/ecosystem.
CC's: A system can be described in terms of its components and their interactions. For 5th graders the easiest of relationships to show in my opinion is feeding relationships. However, when we start addressing the different types of relationships such as parasitism or mutualism students really start to look at an ecosystem as the interaction between living and nonliving in more depth.