"improve his behavior" is a correct and usable phrase in written English.
It is typically used to announce or discuss actions taken to modify someone's actions or conduct. One could say: "The teacher has been working with the student to improve his behavior in class."
He needs to improve his behaviour.
He needs experience and he understands that he needs to improve his behaviour.
Townsend, the article could be seen to continue, had learned his lesson and "indicated a willingness to improve his behaviour in future".
"We know that Mario is a top player but he should improve his behaviour.
But the Manchester City boss has warned he must improve his behaviour to get back on to the international scene.
Manchester City manager Roberto Mancini has challenged Mario Balotelli to improve his behaviour in the new year.
While this was going on, the Home Office and Rampton high-security hospital refused even to assess him and said he could have hospital treatment only if he improved his behaviour.
He was first cautioned by the police around that age, for stealing sweets from a shop, and paid no attention to his parents' requests that he improved his behaviour.
It provides a mobile interface to the console game's spoof social network LifeInvader; lets you customise cars to be delivered to you on your console; and includes a virtual pet mini-game with Franklin's dog Chop that – if you stick with it – improves his behaviour in the main game.
Halfway through the academic year, after collecting the various assessment forms, each student writes a reflective essay in which he or she summarizes the judgements obtained, reflects on differences between these judgements, determines major improvement points and describes an action plan to improve his or her future behaviour.
