We coined the term “mobile lessons” for lessons held outside of “artificial” environments as classrooms. During these lessons, all actors are mobile and must move to do the required tasks. Themes tackled in such lessons may be as varied as geography, history, ecology, dialects in linguistics... Mobile lessons are not a new teaching strategy, but new mobile devices may render it more efficient and more attractive. The aim is to place students in conditions germane to the ones in which experts work. We implemented in Java a software for creating and using mobile lessons and for monitoring students on the field.