This activity explores how distances and areas of convex polygonal plots of land (and concave plots with modification) can be determined using a GPS, The Geometer’s Sketchpad, and Excel.

Mathematics:  This activity involves measurement of longitude and latitude, the distance formula, Heron’s formula, and areas of convex and concave polygons. 

Mathematical Thinking:  Conversion of differences in longitude and latitude to miles, subdividing regions to determine areas, devising a spreadsheet-based general method to calculate areas of polygons.

Technology:  The activity utilizes the position features of a Global Positioning System, basic construction and measurement features of the Geometer’s Sketchpad, and a basic Excel spreadsheet.

Sample Screenshot:  A spreadsheet using Heron’s formula to calculate the area of the rectangular lot, subdivided into two triangular regions, of Lambeth House at the University of Virginia.