My suggestion, is the school an accredited Montessori? Many use the name and say Montessori method, but are not accredited.

DD3 is in the bottom 15% of age in her 3-5 year old class. Next year she will be at about 70%. So there will still be half a dozen kids older. Some not much older, but a a few will be a year older as some spend kindergarten there. It is not that she doesn't like to be the older "leader" but the novelty of hanging with younger children wears off quickly. And also, she likes to "work" (their name for their projects) with a peer who thinks like she does. Her best friend, a little girl about the same size, DD3 is a little small, and same energy, is generally not a child she "works" with at school. They will play in the gym together during gross motor period.

Check out if they are as serious about using these terms. Then they will probably have the right Montessori materials that your son can push his math skills and puzzle skills.

If they are just starting out, you probably can't meet the teachers. If you come in with a skill book of what your son can do, they should be able to accomodate. If they are real Montessori.

Ren