Aggregate behavior and system dynamics models can be used effectively to explore an ADI activity centered around osmosis and its role in establishing equilibrium across a semipermeable membrane. Aggregate behavior models can be used with modeling software such as SLNova and agent-based models can be constructed to look at the way a large array of individual particles produces an aggregate behavior for the entire system. System dynamics would also be effective for looking at a stable equilibrium across cell membranes, and how the concentration of solutes provides the mechanism for a feedback loop.
Students using aggregate behavior and system dynamics models can be provided with information on the way a cell membrane is formed. They will first be given an example of a feedback loop in a cell that goes to a stable equilibrium. Additional activites can be centered on asking why a cell needs this equilibrium to function. Students can be provided with a base model but also guided to construct additional models that allow them to adjust the concentrations across a membrane to observe osmosis in action. If time allows, students can also observe feedback loops in general and see what would happen if the equilibrium was unstable (i.e. a negative feedback loop vs. a positive feedback loop).