Same in China (Shanghai). Same 30 to 35 students in the same class would do 1st to 6th grade. Then you'd usually go to a different school for 7th to 9th grades,

Same in China (Shanghai). Same 30 to 35 students in the same class would do 1st to 6th grade. Then you'd usually go to a different school for 7th to 9th grades, then take a test to get into a high school for 10th to 12th grades. All three would have the same class you'd stick with, usually with way more intra-class interaction than inter-class interaction. Sports was usually one thing that was more inter-class, but that was it.