Hello Jesse,
I have had some similar experiences with my DS8. He is PG and is in a full time gifted program. He has skipped a grade but does not find the work hard. However, for the first time this year he started having problems in school. He started getting low grades. One day he came home with a D in social studies - he could only find 1 of the 6 papers he was supposed to hand in for a project. He is a whizz at math but came home with some Cs and Ds - he would just 'not see' several questions or would read questions wrong (eg subtract instead of add). He would have some papers where nearly every answer was wrong. Apparently his teacher would discuss a topic and then everyone would fill out the answers. However, he had absolutely no recollection of her discussion. He would just pull out random answers out of his head.
He would frequently forget to take his lunch to the cafeteria.
The last straw for me came when his teacher finally told him he could not go back to the classroom to get his lunch and would just have to eat at the cafeteria. What she didn't know is that he would rather starve than eat there...and that is exactly what happened. The poor kid never said anything and just went withour food the whole day.
So...I finally had to face the fact that this was not just a phase or a lack of maturity.
He was diagnosed with a deficit in auditory closure and inattentive ADD.
Some things that helped with the auditory issues were:
1. He wears headphones in class when working so is not distracted by noises
2. He sits near the teacher and she makes sure that he can always see her face
3. He does not sit near potentially noisy areas eg air conditioner units, windows
4. The teacher tries to make frequent eye contact. When she is saying something very important, she ensures that DS is looking directly at her.

In terms if the inattentive ADD, I was completely against using drugs. However, the gifted teacher who has worked with gifted children for over 20 years and herself has 2 grown up gifted children had a discussion with me 'as a parent and not as a teacher.' She finally medicated her daughter and said it was 'like a cloud had lifted.' My ped then also stated that she felt DS would benefit from meds. She said she had seen kids start to dislike school and eventually fail. They started getting punished for issues that they could not control eg No recess because child did not listen.
Long story short, I eventually put DS on Concerta. Wow. There was an immediate effect. He is doing so much better and is once again happy in school. There are side effects and I would still rather he wasn't on anything but right now he really does NEED the drugs. Pehaps I will try an alternative at some point. I chose not to give him his meds at spring break and plan to take him off during the summer. His inattentive ADD is not a problem outside school so I thought this was best.

(By the way, my son isn't always inattentive either. He can read 'fun' books or play video games for hours.)

Hope this rambling post helps!