Awalk, my 7yo son sounds exactly the same too. He's very bright and has accelerated math classes where he focuses because it is highly student-teacher interactive. But for unaccelerated work especially related to writing, he balks and drags his feet.

For the longest time, I thought he had ADHD. His psychologist didn't think so because of his giftedness, but I could see the daily lack of focus, the staring and smiling into space when he was supposed to be doing homework, and I was getting a lot of complaints from school. Getting him to complete simple tasks is difficult because he seems not to hear, so you can imagine how it is in an environment like school.

What he does have is a significant vision issue with very poor visual discrimination. He also has sensory issues and has poor gross motor skills. His OT said his vision profile is that of a dyslexic, but he isn't (he's reading the Murderous Math series now). He does however, have the other symptoms of a dyslexic (no sense of time, poor auditory processing). And because of his vision, writing is tough too. We're working to get this corrected, and in the meanwhile, I'm planning to homeschool him within a very tactile environment.

Awalk, I completely agree with the other posters to investigate further. Good luck on your search!