Interesting. Here, many kids who take AP bio take it concurrently with honors chemistry, that seems to be the most common pathway, generally done in Soph year. Our school has also let a few kids skip honors chem and go straight to AP chem, though I think they were advised to self-study some chem over the summer.
It depends on how it's taught. And I expect taking Chem & AP Bio at the same time would probably work if the teacher is expecting it. My DS16's H.S. it's already an acceleration to take Honors Biology as a 9th graders, non-honors kids take Earth Science & Biology as a sophomore. And new policy students can't double up in science until junior year, and must have two years of H.S. science before taking any AP science courses. So juniors who started in the non-honors sequence may be allowed to take AP Bio & Chemistry concurrently.
My question for the OP is what does your son want to to take? What else does he do? How much time does he want to spend studying vs. other extracurriculars. How does he feel about it. Sounds like he has skipped a grade already, would he be happy going into a class with H.S. seniors? (In my DS's school AP Biology is taken junior or senior year.)
