Thank you all~
Howdy- Yes definitely that was what was happening last spring with Algebra back in middle school. He was starting to crater and it turned out he was not absorbing anything in class. We know it's better now but given that it's block schedule, he has 75 min classes and I'm worried that he fades toward the end of a class period and definitely toward the end of the day. We are going to talk to his doctor about upping the dosage. thank you so very much for your kind input.

Platypus--Yes that is me! I feel so much empathy for you. I especially feel for your son regarding his inability to pursue his passions for math and physics at present. We are the same but with biology and science. I'd love to also reduce the homework. So far, we've identified one culprit which is Bio Honors, supposedly the most difficult class that even the super organized and high achieving kids complain about. He has block schedule at his high school so only has it every other day but they fly through the material and do double the work in each class. It's just so frustrating trying to help him keep on top of this class in the midst of everything else. Case in point, we worked hard with him all weekend and Monday to study for three tests he had Tuesday. We had everything planned out. He had written his Lab report all weekend and tried to get ahead of some work so he could just study Monday. Then boom, pop quiz in Spanish. Pop quizzes don't work for him so he failed it and it was so upsetting because he felt like he had carefully managed everything that weekend. (this is after failing two bio tests).
Next week, he has bio three days and he has a test EVERY SINGLE DAY in it plus another lab report and other stuff due in it. This is aside from the Geo H homework, Eng. 2H essays and tests, Spanish Unit test, and other stuff due.
It's just too much. We discussed dropping the Bio H and going into regular bio but he doesn't want to because he's embarrassed. But given the little time they spend on each chapter, I don't know what he's getting out of it anyway.
Your post really helped me to see that I need to let go of what I thought it would be like for him.
He does have the ability to take classes in the summer and online so we are going to have him do stuff like theology (it's a Lutheran school) online during the summer to lighten the load during the year. A 5 year plan for high school is a good idea!

We are also trying to figure out accommodations. Oddly he doesn't have trouble finishing tests but maybe if he had more time he'd think about the answers more deeply and actually get more correct.
I also connect with your comment that he'd do better if he could. I heard a great podcast on Tilt about that. We try to keep in mind that he'd do everything he is supposed to if he could. He just can't hold it in his head long enough on a daily basis.
Interestingly, Spanish 1 is giving him trouble because he is not absorbing it well in class and given that it's, well literally a foreign language to him and so much of the teaching is done in class, I think it becomes an additional barrier to learning it later in class.

I truly appreciate all those links. I'd read lots of Barkley and read Smart but Scattered over the summer and implemented some of those strategies. The Seth Perler site was very helpful.
I think even though I really boned up over the summer, it did not really hit home until high school started. Then it became "Oh, I see what they mean now".
It seems like we will work with him extensively and think that he's got it down now and then he'll take several steps back.
I think I'm just tired because basically I come home from work, we look at what he's got to do and spend the next 5 hours working. And I spend half my work time worrying about him which is not good for anyone.
I hope things work out for your son. Please keep me posted on any helpful accommodations you come up with and I will share anything I develop.
I'm especially interested in ways to help him retain information he learns in class.

best wishes to you and your DS.