You might sit with him and brainstorm. DD has been having some health problems this fall and is tired and forgetful. It's gotten kind of bad. We asked her to think of ways to solve this, and she is writing things on her hand in ink at school (like "bring SS boook home") the minute they come up. It's not what I would have chosen, but it seems to work for her. She also has a nightly list she has to go through before bedtime (written up) to help her remember all her responsibilities.