National Geographic
National Geographic: Measuring Distances on a Map
Activities will enhance students' understanding of how to read the map scale and apply it to measuring distances between locations.
BBC
Bbc: Landscapes: Scotland: Map Skills: Scale
Lesson for elementary students on map skills uses a map of Scotland to teach about the concept of scale.
Other
Centre for Topographic Information: Map Scale
This resource uses illustrations to demonstrate scale. Check out the links to the The National Topographic System of Canada and the Aerial Survey Data Base.
Rice University
Rice University: Cynthia Lanius: Mathematics of Cartography: Scale
Definition of map scale with related cartography links and activity at Mapblast in which students create maps of their own and determine distance and scale.