[perlgeek]

> As most Montessori schools are private, my impression is that the variance in the quality of Montessori implementation varies considerably

Having gone to a different kind of "alternative" school (Waldorf / Steiner), I agree 100%.

Variance in quality among teachers was pretty high, higher than my children's public schools.

Sadly my school was also used a bit as dumping ground for children who failed in the public school system, so at least in the later classes most of the newer students were below-average in performance, making progress slower and classes more boring.

Switching from an "alternative" to a public school (after 9 years for me) was a pretty big culture shock.