Model It

Model-It is a simple modeling program that is a great precursor for building Stella models. Model-It starts out as a concept map.

On the Plan screen students can choose names and icons (any jpeg file) for their components. Variables must be identified with each Object.

In the Build mode all objects with Variables can be connected with Relationships. The relationships can be quantified directly or generally. For example, as Population Growth increases, Vehicle Use increases by more and more or about the same. Initial values can be set at this time also.

Once the relationships are defined the model can be tested .

By selecting Meter and clicking on the desired object, a slider will appear with the preassigned value. This value can be changed.

The Test is run by clicking the Play button. After about 5 time steps the values do not appear to change. We have used a Years object to step time additionally. If the Years meter is stepped up by 10 or 20 years the dependent variables will change appropriately. Each object that has a meter open will be graphed in the Simulation Graph. This graph area can be enlarged to get a better look at the changes. The graph is not quantified and there are some other limitations to the program but it is Freeware and a great intermediate step to Stella.