DD's school has 6 classrooms and I believe it breaks down something like this:
Infants 0-18 (if a 15 or 16 month old is showing signs of readiness to transfer to the toddler room, they also allow that). I believe they said 9 infants max.
Toddlers 18-24 mo. (This is one of the transition/normalization rooms. I also believe they aren't strict on age requirements +/- a couple of months). This class has 6 or 7 students.
Twos - 24-36 mo. and some 3 year olds that aren't using the toilet 100% of the time. This class has around 12 - 15 students.
Preschool class #1 - slightly more advanced two year olds to near 5 year olds. All are free of diapers and pull ups. (this is DD's class and also the preschool transition classroom). Class has max of 12 students.
Preschool class #2/Pre-K - 3-5 year olds that are normalized (this will be DD's class in Aug.). Class has max of 24 students.
Kindy 5-6 year olds (maybe some 4 3/4 year olds who turn 5 by Dec of that school year). This is a new program for the school this year and they currently have 15 current students enrolled, but will probably max out the classroom at 24. I believe the state max on public K class sizes is 21.
2 of those classes are smaller transition/normalization classrooms with less than 12 students. The toddler transition room has a ratio of about 6:2. DD's class has 12 students enrolled, but not all go 5 days/week. She is usually in a room with at least 6 other children, so most days it's a ratio of 7:1. Because she was new to Montessori, this has worked miracles for her shy and sensitive personality. I think the smaller class size has given her so much confidence and for her to become normalized. The larger preschool class has 24 max with about 15 that go 5x/week. That classroom has 1 head teacher and 1 assistant, so typically it's 15:2 or 21-24:2. I'm thrilled that in August they are moving her to this classroom because honestly I feel that she will get so much more out of a Montessori education in a class of 24 vs. 12.
One of the reasons that I loved DD's school so much is because of their transition rooms. For a child new to preschool or Montessori, I think those first months of normalization need to be in a peaceful low key atmosphere. But once that happens, a class size of 24 to 30 would be more beneficial for the reasons freistms said in her post:
|A typical traditional Montessori classroom has one director for as many as 30+ students. Montessori classrooms are atypically large in comparison to traditional preschool classrooms because the children are learning both independence (self-directed work) and cooperation (older students helping and modeling to younger students, students working together peacefully).
I hope that helped a little.