How To Reduce Aggressiveness And Improve Concentration?

my 9 year old son is hyperactive- I thinks so. I think he has good IQ but is unattentive in school. everytime he blames other students that someone pushes me, takes off my pen etc. may be sometimes i think it is true because though he is very aggressive, short tempered at home, reacts fast in anger, but outside he is a little bit submissive. please advice