For a classroom of a dozen 3- through 6-year-olds, things are surprisingly quiet inside Wildflower Montessori. The most audible sounds, though still hushed, come from two small boys sitting on the hardwood floor next to a tray of wooden cursive letters. The boys are creating their literacy lesson plan for the day: learning to spell “crazyman.”

Inspiration comes suddenly and passionately, as the best ideas do. “Can we make ‘crazyman’?” the older boy asks. “I know what C looks like,” the younger one says, sounding out the harsh consonant and picking a C from the box. “Yeah, that’s easy,” the older one replies.

Head of School Erin McKay approaches the students and lays a cloth on the floor for them to arrange their letters. “Crazyman,” the teacher says. “Who is that?” The two boys smile at each other. “Nobody!”

Nearby, other students are pioneering their own lesson plans, though they’d hardly call them that. A boy leans over a mirror and sketches his portrait. A girl lies on the floor, labeling the countries of South America on a map. Another girl makes tea.

Students guiding their own learning with minimal teacher direction — it’s a personalized learning dream. But this is a Montessori school, following a century-old model that has been doing personalized learning since before it even had a name. That model was the creation of physician and innovator Maria Montessori, who opened her first school in Rome in 1907 and built educational materials around her belief in children’s natural desire to explore their world.

Wildflower Montessori is part of a chain of micro-schools that take Montessori’s model a step further, operating as one-room schoolhouses, led solely by teachers, that aim to make personalization a definition rather than a description of education. Each location supports three grade levels, and although the majority of students are under age 6, ages range from 14 months to 17 years old, depending on the school.

“We are all special and unique, and the fact that we stick the word ‘personalized’ in front of ‘education’ and make it a topic is its own profound comment on where we are and how far we’ve gotten away from common sense in education,” said Wildflower CEO Matt Kramer.

Wildflower schools populate one- or two-room storefronts, creating a micro-school spin on the Montessori learning model.

Today’s typical school design is far from personalized, he said. Large buildings with hundreds, if not thousands, of students. Children working on the same material at the same time of the day and year. Teachers with more parents and students than they can possibly develop relationships with.

That was the landscape former Google head of personalization and MIT Media Lab professor Sep Kamvar encountered when he tried to find a school for his young son in 2014. Dissatisfied with what he found, he developed the Wildflower model: a school led by two veteran Montessori teachers who would teach no more than 25 students. The teachers would direct the school and the students would direct the learning.

From that first location in a Cambridge storefront, the Wildflower network has grown to encompass 11 schools in Massachusetts and Puerto Rico, with more to open soon in Colorado, Rhode Island, and Minnesota. The Wildflower Foundation raises millions of dollars from donors like the Walton Family Foundation and the Chan Zuckerberg Initiative to partially fund the schools and to provide startup grants for teachers who want to open a school of their own, following Wildflower’s open-source model…