Well, from your tone, it sounds like you don't want her to continue there? The law states that you are required to provide an education and yes, you get to decide what that consists of. We homeschool and the requirements are that we teach Reading, Writing, Math, Spelling, and "good citizenship", whatever that looks like :) The only other stipulation is that we do it in a "bona fide manner". Homeschools are considered private school, as would be your Montessori or any other school like it.

Realistically speaking, a Montessori education, accredited or not, is probably superior to any public school around, especially for a 6 yo. I love Montessori and would love for my little ones to have had that. Maybe you could go in and talk to the administrator and see what they do at that level. You might love it!

Edited to add: the other thing you might want to consider is continuity for your daughter. You say she's been there since 2002...that's a long time for one so young. That's her world. With the divorce and other instability in her life (is she moving homes? other changes resulting from the divorce?), you might want to leave her there just for the sake of normalcy. Fewer changes at that age is best. Just a thought...