– When the doors open, there’s a blast of cold air, and the hallway is suddenly filled with rosy-cheeked kindergartners.

Snow pants swishing, they hustle past their principal, Jill Rollie, who is handing out high-fives, greeting students by name and problem-solving on the fly.

“Hi Jackson!” she says. “Hi Pablo! Oh no, you lost your glove.”

“Hi, Mrs. Rollie!” several kids yell in unison. A few offer hugs. Nearby, a teacher is gently directing traffic, pointing the swirling mass of puffy coats and knit hats toward red cubbies labeled with their names. “Boots off!” she announces cheerfully. “Snow pants off!”

It’s almost lunchtime for these kindergartners, just as it is at elementary schools across Minnesota. But at this school, unlike almost any other in the state, it’s lunchtime only for kindergartners. At the Woodson Kindergarten Center, there are five dozen adults, 367 kindergartners — and that’s it.

Everyone and everything in this building, from the teaching staff to the designated play centers, is focused exclusively on kindergarten.

At a time when state lawmakers and education leaders have sharpened their focus on early learning, Woodson’s unusual approach stands out. The Austin school district pioneered universal, all-day kindergarten nearly a decade before the program went statewide. And as the southeastern Minnesota city’s population has transformed, becoming home to several waves of immigrants, the kindergarten school has become the district’s way of welcoming all its students and ensuring they’re ready to tackle first grade — and beyond.

Rollie, the principal, said Woodson students speak nearly 20 different languages. Putting them all under one roof, allowing them to develop friendships and learn alongside one another, she said, is an asset to both the students and the community.

“It’s a celebration to see the diversity grow within our district,” she said. “And to have them all be together in kindergarten, it’s an opportunity for everyone.”

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Woodson opened in fall 2005, a time when Austin school administrators were seeing their student demographics shift and enrollment swell. In just a decade, the district’s population of students of color had jumped from 5 percent to 23 percent. (Today, it’s 48 percent.) Austin, a meatpacking town about 100 miles south of the Twin Cities, had been changing for even longer. Since the late 1980s, a steady stream of Latino, African and Asian immigrants had been moving in to work at the city’s two big meatpacking plants.

John Alberts, Austin Public Schools’ executive director of educational services, said the district’s superintendent at the time was particularly interested in early learning — and especially in the benefits of all-day kindergarten. Back then, only some Minnesota districts offered all-day programs. In many cases, parents had to pay a few thousand dollars to enroll their students.

Austin school leaders wanted to make it free and available to all families. And because the goal was to help launch all the district’s students in the same way, they figured it made sense to put all of that activity in one place.

“[We thought] this would be something to help jump-start all of our kids out right,” Alberts said.

While other districts followed Austin’s lead in moving to all-day kindergarten, few have attempted to put all of their 5- and 6-year-olds in a single building. A handful of districts around the state have buildings shared by prekindergarten and kindergarten students. But according to the Minnesota Elementary School Principals’ Association, there’s just one other kindergarten-only school in the state: Bemidji’s Paul Bunyan Kindergarten Center. That school, however, is set to close next year.

Change may be ahead for Woodson, too. In April, Austin voters will weigh in on a nearly $25 million bond referendum that would finance a new early childhood addition at the school, among other improvements in the district.

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For now, however, Woodson is all about kindergarten.

Because the entire student body is still learning to read, classrooms are marked with signs featuring different colors and animals. Across the building, teachers speak in a gentle, sometimes repetitive language that’s all their own, greeting their students as “friends” and urging good behavior with phrases like: “Use your walking feet!”

There are two large rooms designated as play centers, where students spend time every day. Often, playtime is an open-ended period where the kindergartners can create their own games and activities. Though much of the day is spent on traditional subjects — math, reading, science — Rollie said teachers incorporate play into all aspects of the day.

While the kindergartners are busy picking up the academic building blocks for the rest of their school career, they also are figuring out how to cooperate and collaborate, take risks and explore the world around them.

“We take very seriously the social skills that come with school and interacting with each other,” Rollie said. “That’s huge in kindergarten.”

On a recent Friday, students in one of the play centers crouched in small groups around visiting music teachers, who’d brought along several instruments. They giggled at the high-pitched sounds of the piccolo and the booming belch of the tuba. One by one, they eagerly took turns strumming a harp, their arms barely stretching across the strings.

The kindergartners’ excitement was palpable — and it was just about everywhere else in the building, too. In classrooms, they eagerly raced their friends to complete math work sheets and traded stories about how much they enjoyed reading time. (A particular favorite: Wednesdays, when adult volunteers from Hormel, the city’s largest employer, bring books and serve as reading buddies.)

Teacher Alisha Galle, who has worked at Woodson since it opened, said the environment gives teachers the rare opportunity to have more than a dozen fellow kindergarten teachers with whom to problem-solve and plan. (This year, the school has 16 classrooms.)

She said that means every adult in the school is working together to figure out what kindergartners need most to have a successful day and to ensure they get it. Something small, like coordinating to make sure every child gets a hello in the morning, can go a long way.

“We know that there are kids that come to school with a lot of extra baggage and don’t always get that support,” she said.

Former Principal Jessica Cabeen, who now oversees a middle school, said other schools and grade levels can be joyful places, too. But there’s something special in the air in a place where kindergarten is everything.

“I always said we were the happiest place in southeast Minnesota,” she said.