When my DS5 entered Montessori this past fall we were met with some of the same issues. Certain activities could only be done in a certain order at a certain developmental age. Fortunately my son doesn't take no for an answer and told his teacher that he had to start the early readers even though the kids don't start them until the fall of the K year (which he won't start until September). He quickly raced through them all. He pushed the limits and has even completed all the advanced K materials relating to math that the current extended day class never even got to use this year.
In our case I think our lead teacher realized that she was not going to slow down DS5 and he has made huge strides socially (which was her excuse before for not allowing him to work academically at his level). Just last week she told me that she was in the process of purchasing a new reading curriculum for my son to use next year that is more advanced. Not sure what her math curriculum plan will be but she has never mentioned to me that I should slow him down.
I agree with Cathy...are there other school options? No matter what school you choose if the teacher is not on board it will not work. I think after being at that same school 3 years already, if they were going to get your son they would have by now.
