Investigate the user, control, and space segments of GPS with the NASA IV&V ERC Loanable GPS Kit and build a new perspective on the Blue Marble. This session will highlight content and lessons pertaining to utilizing the GPS constellation composed of 24 US government satellites and will participate specifically in an outside activity that will build a user's ability to operate a GPS unit while measuring the circumference of the Earth and comparing to the methods and results of Aristotle and Eratosthenes.