FreeDict is a project offering free translating dictionaries encoded in TEI P5. The databases can be converted into various lookup formats/protocols (DICT, Evolutionary Dictionary, zbedic; this is at various stages of completion and re-coding).
FreeDict is preparing to become open to student involvement: if you are interested in finding markup-, TEI-, language-resource-oriented tasks for your students, please contact the project mailing list.
There is currently no manual on encoding FreeDict in the TEI. Some teaching materials exist. Most databases use very simple markup, some are more complex (see e.g. Swahili-English. Swahili-Polish, English-Polish for examples of more elaborate markup that in some cases needs to be accompanied by separate visualisation/conversion scripts).
From 2000 until 2016 (or so), FreeDict was hosted at SourceForge. Since 2017, SourceForge still holds the old mailing list archives, but all the databases there should be considered obsolete.