There are probably as many red flags (or low-level-orange rather than blazing red!) flags for so many different problems that posting a random list is just going to be confusing rather than giving clarity.

Can you tell us, as DeeDee asked, what you're seeing that you are concerned about? What are you seeing that appears to be an "extreme preference in learning style?" What are the signs you see that make you think he isn't an auditory learner?

polarbear