[sprovoost]

How would you go about testing the business model of each of these apps? Are you able to test it this week?

Idea one sounds most useful to me, if it hasn't been done yet. Given your experience in teaching people iOs development in real life, you could start with that topic.

Normal books have code samples; perhaps the book can have assignments that you can code and run inside the book? I believe there are some web based iOs development or simulator systems out there; can you leverage those? Or instead of running code, just parse the answer to see if it is correct.

Or you can even use crowdsourcing to have humans grade student assignments as an in-app purchase.