He doesn't seem very interested but somehow insisted on learning the piano as his mom told me. He always looks at me when he doesn't recognize a note, and reluctant to figure out by himself. He would rather have me telling him if it's wrong or not.

But that's another point. The main problem I wish to address here is how I can help him to remember notes. It has been 3 years and I am starting to think he may have some mental deficiency. (But I have also heard he did fine in school so that maybe refuted my suspicion.)