Refer to your files for a map that documents your site. The catalog also indicates stores and map libraries where Minnesota maps are available. Costs of the maps will vary. Ordering directly from the USGS is the least expensive. Minnesota DNR has aerial photographs for sites in many Minnesota counties.
Enlargements are available.
Call or write for an updated list of available counties, ordering information, and costs. Try making a three-dimensional model of your school's watershed. Younger students will benefit especially from being able to visualize what happens to a water droplet placed on the model. The three-dimensional watershed model can be used to teach about water pollution and comes with educational activities.