Our exploration of the Tyee Campus ecosystem concluded with a return to modeling energy flow using Microsoft Excel 2013.  Students worked individually to construct an energy flow model using a worksheet which provided the calorie requirements of a variety of organisms found on our campus.  The worksheet also included the Excel formulas to connect the various pieces of data into a model.  The lesson provided students with an opportunity to practice using the formula functions in Excel, taught them how to create a linked graph of the data, and asked them to derive explanations about why organisms are found in numbers approximating what might be anticipated by their understanding of the trophic pyramid.