Berkshire and NMH both sound like potential fits. I would worry re Putney if he needs executive functioning help - it is very unstructured. NMH and Berkshire both offer some support for executive functioning type things if he needs more support beyond the already structured boarding school environment. NMH classes are nearly all discussion based which is why they have longer blocks and just 2 semesters. This was a huge advantage for my DD. NMH is also one of the more laid back BSs and the dorms participate in “Hog Olympics” and function somewhat similar to Lawrenceville’s houses. My daughter was in the same dorm all 3 of her years and formed a tight bond with the faculty. PM if you want to reach out - I know they offer linear algebra and number theory plus likely independent study options. For kids who need just a little support NMH is a good choice. Berkshire has a more robust support program that you apply to join. NMH has a very strong music program and is known for its many singing groups.