in response to "myexcuse," slowing down is a good thing. and being able to slow down one's thoughts is a good thing as well.
so your son can't type 140 wpm. this isn't always a problem. in fact, it could be a good thing. if he can't type as fast as he thinks, then perhaps it's because he thinks too fast.
i had that problem. i blamed it for a lot of my academic failings. do you know how i fixed it? i slowed down my thinking when it came to writing.
now my writing is better. instead of blurting out whatever i feel, i revise before i write it.
yeah, he's a little kid. and rambunctiousness has its place. but not in an essay. who was that said good writing is an overflow of powerful emotions remembered in tranquility? 140 wpm is hardly tranquility.