What happens prior to the Tantrums, why does he throw himself on the floor? . when he does this and if there is no cause, put him in time out ,set a chair on one sideand sit him on it, and tell him he should stay there,till he is quiet and sorry, he will yell and he will come off, do not respond ,quietly put him back , over and over if you have to, There is usually a reason for the acting out, so check what is happening and what triggers the behavior.