Greg - congrats on the new site! the best advice I can give you is keep at it. You might not get much feedback for the first 2-3 years
But, if you can keep it up, the effort will begin to pay off.
The activities seem pedagogically sound, but for a student, you'll need a very motivated self-learner to keep as your audience. Do you have the background software/server ability to make it a point based system or quiz type activity?
It might be good to have 5 questions for them to answer. They can try those and then get 5 new questions. 3 cycles of something like that might keep students more interested.