Montessori is just a method of education that is based on hands on learning and collaborative play. In Montessori classrooms children make Creative choices in their learning while the classroom and the teacher offer age appropriate activities to guide the process (more like a facilitator) children work in groups and individually to discover and explore knowledge of the world and go develop their maximum potential.
However, many schools in sg, even though they call themselves Montessori are not real Montessori