About Arcadia Montessori School The Arcadia Montessori School was founded in 1963. It is the oldest Montessori School in the San Gabriel Valley. We have no religious affiliation of any kind. Linda Pilmer (who is a credentialed school psychologist ) has been the owner of the school since 1980. The director is Cheryl Roberts who has been affiliated with the school for more than thirty years. Dr....