Note: it seems like OP's goal is for the kid to prep but still take the class at the kid's high school.

Please also ask if such external classes can appear on your kid's school transcript. In our public school system, they cannot, sadly. If that's not possible for your school, then make sure to highlight it elsewhere in the college applications.

I found this course provider that looks quite legitimate. My son is planning to take half of AP Physics over the summer through this provider.

Auditing/accessing course materials is very inexpensive (less than $100). To take the class for credit on a real transcript would take two semesters of asynchronous class and be about $800.

https://www.ucscout.org/courses/apchem

We don't live in DC. We live in the South.

What school are you at? Why not just take it through dual enrollment? Or could take it at UMD.

DS wants to take AP Chem next year, but his first year of Chem at his school was horribly taught. Unfortunately, the same teacher is also teaching AP Chem next year. Can anyone recommend a good summer online course that will help him prepare for AP Chem? Can be online or in person.