I ran across a nice set of Islamic Studies lessons at AbuKhadeejah.com. They were written for ages 13-16, but would also be useful for adults as well. They are brief and generally have a set of questions at the end.
I am planning on using some of these with my kids and I couldn't find an index of the lessons, they seemed to more so be separate blog posts, so I made up an index with the lessons in order. (There may be one, I just couldn't find one).