Encourage him to act like his hero. For example, if he enjoys watching Superman on television, let him pretend that's who he is. Sometimes, children don't try because they lack confidence; pretending to be his hero can help him find hidden confidence within.
Help him learn more about his interests. For example, if your child is interested in computers, buy him a couple of books that teach him how they work and what makes them tick. This will stimulate reading skills, which translate well into his school studies.
Let your child run around outside and play on the lawn for a few minutes before doing homework. According to a 2001 study, children focus on homework better after spending time with nature for a bit.
Praise what your child does pay attention to. Getting upset that he won't pay attention to his studies isn't productive, but maintaining a positive attitude is. For instance, if he constantly watches what other kids are doing, praise him and let him know that shows how caring and concerned he is for his peers.