[simiones]

At least in my country (Romania), the norm in all public schools is to have the same set of ~30 children you'll go to school every day with from grade 0-1 (6-7 years old) to grade 8 (14 years old). Since there are very few to no electives, you'll spend ~all of your time in school with all of these kids every day for 8 years - and virtually everyone in the country has this experience (private schools are very rare).

Edit to add: the whole school would have significantly more people, typically around 5-10 30-pupil classes for each of the 8-9 years. So perhaps the difference is the total number of children in the same school - though typically interaction between different classes, even of the same year, was far less than within-class.

[rejectfinite]

Same here in Sweden. All school is like this. Not just Montessorri.

[morgelgluff]

It used to be the norm to mix up the groups every three years, when transitioning between low/mid/high school stadium.

I appreciated that change of social dynamics every time.

[wholien]

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.

[bawolff]

Yeah, i went to public school in canada. It was all the same kids up to grade 8. Each year had basically 2 classes of about 27 kids each.