I was just informed of a resource I hadn't found yet. I love it when that happens!! It's called smallcatechism.org and it is an online course that was written by an LCMS pastor (Rev. Thomas F. Fischer) and would be ideal for those who only have a couple of students (1 or 2), have a student with special circumstances who cannot attend class, or need supplemental material. It is not free.
I checked out some of the lessons and there's a LOT of good information but there's also a LOT of reading and it is not interactive at all, nor are there many images. There are quizzes at the end of each unit that are primarily multiple choice and true/false so they do not get past the information recall stage. There are some class discussion pages that do include a few questions for reflection but in my "hard to please" opinion as a professional educator, not enough for me to feel they're really thinking about the material. You might want to add some.
BUT, as I said, this site would be good if you only have a few students or students with special circumstances. You could use it to have them preview a lesson before class discussion, you could have them work at home and come in once a week where you could have a discussion where you have the opportunity to shape their understanding and can press them for reflection. Remember that it's in the discussion that kids learn most, not in the recall of facts. You need to make them and sometimes help them reflect on what they're learning!