In this directory page, you can get listed if you provide FREE training material for QGIS.
The general idea is to be able to (re)use material from each other.
Educators are encouraged to use/mix/add material to the QGIS Training Manual.
The official Training Manual can be found here: http://docs.qgis.org/latest/en/docs/training_manual/index.html
Tutorial material, originally developed as part of a workshop for the Ecology and Evolutionary Biology Program at Texas A&M University (produced and maintained by Mike Treglia): http://mltconsecol.github.io/QGIS-Tutorial/
In-person training material, originally developed for the New York City Department of Transportation by Datapolitan:
Roberto Ilacqua wrote a manual for image classification in QGIS: Manual do QGIS para Classificação Supervisionada de Áreas, full version, 200 p - 2017 or Manual do QGIS para Classificação Supervisionada de Áreas (short version), short version, 34 p - 2017.
The French Ministry of Environment supports the QGIS project. Training material from them is available here: http://www.geoinformations.developpement-durable.gouv.fr/qgis-supports-pedagogiques-r947.html
Other resources from them are available here: http://www.geoinformations.developpement-durable.gouv.fr/qgis-r625.html
The French National Center for Scientific Research (CNRS), created an online QGIS tutorial: http://ouvrir.passages.cnrs.fr/tutoqgis/