When i moved to the US i was 15 and had just completed the first quarter of 9th grade in Singapore. The local High school i went to had me "skip" to 11th grade for 2 months taking a bunch of AP classes going over stuff i covered in the 8th grade in Singapore.
My 12th grade was spent taking Late Arrival, PE, US History, US Gov't, PE again, DECA, Early Dismissal so i could fufill the school's requirements for graduation.
Total waste of a year. But it was a pretty good time
alf