Watershed Dynamics
Eutrophication STELLA Model: Troubleshooting Guide

The following describe solutions to problems that students may encounter as they use the eutrophication STELLA model.

1. Students cannot open the STELLA model:
   The demo STELLA program may only allow one model to be open at once. This may include any blank “New” model. To make sure that no models are already open, choose “Close” under the “File” menu, and close anything the program tells you is open. Then choose “Open” under the same menu, and select the Eutrophication model file.
   
2. Students’ screen doesn’t resemble the description in the activity:
   Students may have inadvertently opened the “Model Construction” layer or the “Equations” layer of the model. To return to the “Mapping” layer, find the small white box near the top of the left-hand grey margin. This box contains a triangle or two. Click on the upward-pointing triangle. The screen should change. If it still does not look correct, click on the upward-pointing triangle again. If there is no upward-pointing triangle, check to make sure that they have opened the Eutrophication model.
   
3. Students cannot move sliders to desired values:
   In the middle of the bottom of the slider box is a small box with a number inside it. Students can click on this number box and enter a value directly.
   
4. The slider number box says “eqn. on”:
   Students may have accidentally clicked on the small button in the lower left-hand corner of the slider box (the button with the squiggle on it). Click on this button again and a number should reappear.
   
5. Students cannot clear the “Results” graph with the Dynamite tool:
   Students may have accidentally “locked” the graph, which prevents its being erased. Make sure that the icon in the lower left-hand corner of the graph is an opened lock, not a closed lock. If it is a closed lock, click once on the icon and it should revert to an open lock.