Geocaching Basics
Alice Christie is the Guru of Educational uses of geocaching. Geography and History are natural fits with geocaching, but try
Geomathing
Geoscience - create a cache that asks the students to learn something about science. ie test water by a stream - testing materials in the cache.
Literature - create a cache with a journal and ask geocachers to add one line to a story in the journal. You could highlight famous people and places.
Environmental - Ask geocachers to identify a plant, tree or an environmental problem.
How do you asses it? Content always comes first. Students post answers online.
Beth Ritter-Guth was the presenter. Much more info on her wikispace.