About Us
Our Story
The Developmental Environment Rating Scale (DERS) was designed by researchers and developmental learning advocates at the National Center for Montessori in the Public Sector. The DERS was originally created in response to a need voiced by Montessori early childhood educators, who felt that existing measures of classroom quality were not well-suited to capture the way teaching and learning happens in developmental learning programs like Montessori. Jackie Cossentino, the primary author of the DERS, set out to create an environmental rating scale firmly rooted in the literature on human development, and sensitive to the complex interaction of children, adults, and the learning environment. The draft tool was reviewed by various constituents both within and beyond the Montessori community before field testing. The electronic version of the DERS was first published in early 2017 and has, in the ensuing years, undergone numerous internal and external reviews for clarity and consistency, user experience, equity, inclusion, and psychometric validity.
DERS Team
Katie Brown, Ph.D.
A researcher by training, Katie Brown has dedicated her career to studying student-centered learning models. She has served as a classroom teacher in district and charter settings, a teacher educator, and a charter school board member. She specializes in online professional development programs for adult learners.
Katie Grabowski
Katie is a dedicated advocate for high-quality, developmental education with over 15 years of experience in Montessori programs as a teacher, mentor, and collaborator. She is currently focused on developing and enhancing tools and resources that empower school-based practitioners to create enriching and supportive learning environments for children.
Katy Mattis
Katy Mattis is an experienced Montessori educator, having served as a guide, instructional leader, and principal in private, charter, and magnet schools. With 12 years at Denver Public Schools, she is passionate about equipping teachers and leaders with the tools to create effective, child-centered learning environments.