The PNT National Coordination Office has developed an educational poster, produced in 2013, which explains the basic concepts behind the Global Positioning System. It is online, downloadable from http://www.gps.gov/multimedia/poster/
It is aimed at science and math students in middle school and high school, as well as the general public.
Full-size prints (35" x 22") will become available in February 2013 for use in schools, conferences, and other educational settings.
To order a free copy for your classroom, please contact Steve Sidorek at the National Coordination Office at firstname.lastname@example.org