A high school course is more supportive, with less independent study/learning requirement, and, of course, it is slower paced. The summer course will not only be faster, but, will probably have seasoned adult learners who know how to do college work. Summer science courses pacing are a challenge even for regular college student. IMHO, I’d go with the high school science, and perhaps, take a summer course in humanities, which you say is her strength.