oh sounds like you are doing the right thing, the important thing to remember is show him the right way...if he throws a toy, have him pick it up, then set it down nicely, if he throws his plate, either take it away right then or pick it up, say "you don't throw your plate on the floor, you push it back if you are done" and show him how to push it back/away from him, and say "all done". It is a common "phase" to throw things at that age, the trick is to "show" them it's not ok.