A simulation classic. Large fish eat small fish. Small fish eat plants. If the large fish eat to many small fish then the small and large fish will die. What makes a stable system and what does stable really mean? Experience the surprising fragility of eco systems as simple as this one.
Open the simulation properties (in the tool menu), run the simulation and observe the number of small and large fish over time.
Look at the behaviors of the large and small fish. Modify the reproduction rates and/or the threshold of dying.
If you have access to a plot package plot a) the number of small/large fish versus time, b) plot small fish versus large fish in a scatter plot. What does the chart reveal?