We moved my son out of a Montessori for second grade, where he had been for 2 years. One thing to realize is that Montessoris are VERY different from a traditional school.
For example, his low scores on math and writing fluency- those are kind of timed tests, which the Montessori totally doesn't do or emphasize. You may just need to at home shore up some fundamental skills the Montessori doesn't give him- like doing math facts, math flashcards, timed tests, etc.
My son really had problems with that at first moving to the public school this year. I created some little timed tests for math at home (1-2 minutes only), and he gradually got better.
We found that Montessoris do not emphasize alot of writing skills, spelling, etc. You may just be seeing that this is the result of his Montessori education. I have my son do 10 spelling words with me each week.
