The educator's (a.k.a. guide) primary roles are to both carefully prepare the environment to reflect the needs of the children and to regularly observe and take notes on the students in order to better prepare the materials and the classroom. The guide observes his/her students to identify “sensitive periods” or moments when a child may have an easier time learning a concept, and then scaffolds that learning need with lessons and the appropriate materials.  There is no expectation that children all perform or learn the same lesson, at the same time, or in the same way. The environment is constantly evolving and adapting to meet the needs of all the children.

Maria Montessori believed that children have a strong innate desire to learn and if they are presented with a rich environment that meets and calls out to their needs, they will be joyful and content in their learning. Montessori believed that teaching need not be something that is forced on children, but instead can be something they cannot wait to do each day. Teachers that are trained in Montessori develop this belief in children and carry it with them in their practice and work with children.

The hallmark of the Montessori classroom is that it is the child’s classroom, not the teacher’s classroom. In the Montessori classroom, there are not rows of desks, instead, children work at tables or on the floor, rolling out mats on which to work and define their work space. The classrooms are designed so that children may be successful in their daily work with tools made of their size and are hung at their level. There are open-ended work times during which the students move freely throughout the environment, choosing what material they want to work on, and engaging in periods of deep concentration around this interest-based learning.

Montessori believed in a natural setting for educating children, this belief can be seen in many ways in her classrooms. Montessori classrooms are multi-aged. For example a child typically starts in a pre-primary classroom at age three, and will stay in that same classroom with those same teachers through age six. Mixed ages allow for children to teach one another with skill and confidence. Another way in which the classrooms are natural and purposeful is in Montessori's lessons and areas of practical life. Montessori's view of supporting the whole child toward independence through practical life experiences is a lesser known aspect of her philosophy than her system of strong academics, but is a vital and important component of the Montessori classroom. Montessori classrooms and teachers are also geared to support and develop a deep sense and reverence for the natural world. 

The classroom is prepared mindfully and from the perspective of the child. Montessori developed rich sensorial activities which are used often with children of various special needs today. There are particular areas and materials that are inherent to the Montessori classroom, and then aspects of the environment that are developed for the particular children of that given time period. This may differ from school to school depending on the training system that is aligned with any one particular school. Each classroom is carefully and lovingly prepared, replenished, altered, and cared for on a daily basis by the teacher for the child.