Double Geopardy

Hi everyone, I'm a teacher hoping to help 6th graders learn geography, lat/lon, etc. with a bit of geocaching - but, being a teacher, I don't want their GPS to do much for them. I'm hoping to find a relatively inexpensive GPS that has lat/lon and maybe a compass, but really nothing more - so that they *need* to move around, see how their coordinates change, and use that to figure out where a cache might be. Any suggestions? Thanks, DLFR