Homeschooling High School
A lot of high school students earn college credit before graduating high school. Several avenues for doing this are available to homeschooled students and a lot of students graduate high school as homeschoolers with several college credits or even a two-year AA degree to their name.
Advanced Placement (AP) courses are a popular option in schools. Part of the reason for their popularity is that high schools get higher ratings if they have more of their students take AP exams and higher ratings can lead to more funding. Note that some ratings aren't even based