Geodesy from the NGS

Geodesy is the science of measuring and monitoring the size and shape of the Earth and the location of points on its surface.

NOAA’s National Geodetic Survey (NGS) is responsible for the development and maintenance of a national geodetic data system that is used for navigation, communication systems, and mapping and charting. In this subject, you will find three sections devoted to learning about geodesy: an online tutorial, an educational roadmap to resources, and formal lesson plans.

http://oceanservice.noaa.gov/education/geodesy/welcome.html