How can i correct my German Shepherds new aggression towords kids.?

i have a male german shepherd that has become aggressive toword children only in the past few weeks. he is 1yr 3m old and this just started. he will be fine around them and then all of a sudden (unprovoked) will freak out.... he is not nuetered yet but will be soon. i am looking to find ot if this is something that has any chance of being corrected and if so, how? i have heard that nueturing curtails aggressivness, but i wonder that now he has snapped a few times if it is more likely to happen? also, if this will get better or worse with age? i am not looking to have him put down, but i really need to ensure that this never happens again. i am willing to try any method. my first thought is to isolate him from children and correct ANY aggressive behavior towords anyone, even if its semi-playful. anyone has any options please let me know. thanks, Nick