WLFEO is correct, some "Montessori" schools are really not true Montessori. There are two organizations which true Montessori schools affilliate one is AMS- American Montessori Society. Their website is :
www.amshq.org/schools.htm for more details. Real Montessori materials include trianomial cube, pink tower, brown stair etc.... Other schools just use the Montessori concepts. Though I suppose that is a bit unfair to true Montessori schools, the name Montessori is not trademarked so it is not illegal for anyone to use. Most true Montessori schools really want their staff Montessori certified.