My 11 year old son is gifted in math (98-99th percentile in achievement and ability testing), but often misses problems due to poor organization, not writing out all the steps, misreads his own handwriting, laziness, etc. It's enough of a problem to prevent him from making A's in math despite his ability. His math teacher acknowledges his issues, but isn't concerned because he gets the concepts. Does anyone have any advice for how to deal with this? He's in an accelerated program and will start taking high school math classes in 7th grade. Obviously I want his GPA to reflect his ability.

Are there tutors that specialize in this kind of issue (executive functioning?), or techniques I can use to help him aside from the obvious advice to line things up, check your work, etc?