Lest We Forget is a series of Adventist History unit studies designed for upper elementary and junior high students. The 5 part series features readings, study/research questions and more. They are all free .pdf files . Be sure to check each link for the separate files.
Lest We Forget – Beginnings of church history
Lest We Forget II – Organization of the church in the 1850-60s.
Lest We Forget III – General Conference of 1888
Lest We Forget IV – The Southern Work , includes links to mp3 files
Lest We Forget : The Total Historical Picture – excellent timeline resource
The Adventist Home Educator 