LIMESTONE — The No. 2 ranked high school in the United States doesn’t look like much from the outside.

It’s inside a sprawling, single-story brick building that it shares with the local elementary school. It’s a lot like other older Maine schools, except that it’s in the middle of nowhere — the end of nowhere actually, past vast fields of potatoes, in the shadow of the former Loring Air Force Base.

The school’s interior is worn. The classroom furniture is old and mismatched. The floors could stand to be replaced, and the walls need fresh paint.

None of that seems to matter to the 145 kids who spend their days — and nights and weekends — there.

Last week U.S. News & World Report released its annual rankings of more than 17,000 high schools, and the Maine School of Science and Mathematics, tucked in the northeast corner of the state, ranked second behind only Academic Magnet High School in South Carolina.

The rankings assessed several areas, including college readiness, reading and math proficiency, and graduation rate. MSSM ranked first in college readiness – 100 percent of graduating seniors are accepted to four-year colleges – and first in math and reading proficiency. The average SAT score here is 1,430 (out of 1,600), and the average ACT score is 30 (out of 36), both significantly above the Maine average.

But those metrics don’t fully capture what makes the school so successful. The success comes from its students, a diverse group from all over the state (and some from outside the state). Most are among the brightest students in their home districts, and they all had to apply for acceptance.

“That we can attract these motivated young teenagers is really a testament to the school’s reputation,” said Tracy Meyer, who teaches chemistry. “I often forget that they are high school students.”

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The school sometimes feels more like a small college than a high school. No bells or buzzers mark the beginning and end of the school day, or the breaks between class periods.

The day begins for most students with breakfast in the cafeteria between 8 and 8:30 a.m.

Ethan Kelley nibbles on a sesame bagel with cream cheese while waiting for his physics lab to start. A junior from Yarmouth, Kelley is like a lot of other students at MSSM: shy, polite and thoughtful.

He learned about the school by attending one of the summer camps hosted there. The idea of a boarding school focused on math and science appealed to him.

“It can be challenging,” he said. “It’s like going to college at 14.”

The Maine School of Science and Mathematics was founded in 1994 as a public magnet school, designed to draw students from other districts who might fit better into a specialized curriculum. Twenty-five years later, it remains the state’s only such school.

Maine residents pay no tuition, only room and board, which costs about $9,300 annually. Scholarships and grants are available, depending on need.

But people still think of MSSM as a private institution, similar to legacy New England prep schools often associated with families of privilege.

Alan Whittemore, the dean of admissions, travels the state every fall recruiting students and said he often has to educate people about the school.

“It’s sometimes hard to describe,” he said. “I think it’s one of those places you have to see for yourself to get a feel.”

In fact, one of the requirements for anyone who attends the school is that they visit first.

Zach English, a senior from Sanford, also learned about MSSM by attending summer camp there. But he didn’t arrive until his sophomore year. He spent his freshman year at Sanford High School.

The biggest difference was the size. His freshman class at Sanford was bigger than the entire student body at MSSM. He went from classes of 25 to 30 students in Sanford to classes of 10 or fewer.  The student-teacher ratio is 8-to-1. He admitted that the school has been an adjustment.

“I think everyone sort of pushes themselves more here,” he said while waiting for his lab turn, which on this day was studying light and wavelength using a laser pointer. “But at the same time it’s not ultra-competitive.”

Grade point averages are not tracked at MSSM. There are no class rankings, no valedictorians. In class, students instinctively work together.

“It feels healthier to not be so worried about where everyone else is academically,” English said.

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Between classes, the hallways are strikingly quiet. The students all have cellphones, but they aren’t staring at them. The talk isn’t about reality TV or relationships or parental annoyance. It’s almost always about something related to learning.

Yet despite the academic rigor, there is a laid-back feel. Students don’t need permission to use the bathroom. No one is likely to get caught fighting in the halls or vaping underneath the stairwells.

That’s not to say there aren’t occasional behavioral problems, but they’re rarely disruptive. Students say the classmates who get in trouble usually end up leaving.

A late-morning class in plant biology was held outside in the woods beyond the athletic fields Thursday. Students looked for animal eggs on the rain-soaked forest floor.

Ashlynne White, a junior from Portland, said she was always interested in the boarding school experience. She checked out some of the more traditional New England boarding schools and got sticker shock from the tuition. MSSM has been a great fit for her.

“We don’t have a lot of drama here,” White said. “I like that.”

Aside from that, she said, there are fewer distractions.

“You can’t go out with your friends to a restaurant or go spend the day at a trampoline park,” she explained.

She paused for minute.

“But it’s not as isolated as people think,” she said. “I mean, we’re all isolated together.”

***

The students are not tethered to campus. There are trips to the nearest city, Presque lsle, population 9,000, which is about 20 miles away and has a mall. It’s far smaller than the Maine Mall in South Portland, but students said it’s oddly comforting to go to Taco Bell, McDonald’s or a clothing store.

They all go home once a month for a long weekend. The school shuts down, and four buses travel south. Asked what they do on those weekend trips home, most students said “sleep.”

Late Thursday morning, a few students sat in an advanced math class taught by Greg Hamlin. They discussed convex hull algorithms. It was dry and complicated, but if they were sleep-deprived, it didn’t show. They leaned forward in their seats and interacted with Hamlin and one another for more than an hour.

Hamlin is like many of the teachers there – highly qualified. He was a software engineer for many years before transitioning to teaching. His daughter went to MSSM and alerted him to a faculty opening.

“She actually talked me into it,” he said.

Hamlin grew up in Aroostook County, so the school’s remoteness was not a shock to him.

Whittemore said most teachers who come do make a sacrifice. Although salaries are competitive, starting around $45,000, and the school offers benefits – such as free housing and meals – that most public schools don’t offer, the area itself can sometimes be a tough sell.

The school’s annual budget is $6.2 million – $3.6 million from state funding, the rest from room and board fees, and a small amount from tuition paid by out-of-state students. This year, there are 13 out-of-state students who each pay $48,600 to attend the school.

Meyer, the chemistry teacher, and her husband, math teacher Todd Smith, said the allure for them has been the students. Each taught at public schools in Texas before moving to Maine.

“You don’t get this level of commitment in most public schools,” Smith said.

Smith also oversees an underwater robotics competition called SeaPerch. Late Thursday afternoon, the students practiced at the full-size pool almost hidden inside the school. The goal is simple. Each team has to create a robot that can navigate an obstacle course under water.

MSSM finished first in the state this year – for the first time in school history – and a group of six students will represent the school at an international competition in Maryland next month.

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Between classes, many students gather in the library, which they call the learning center.

Harrison Walters, a junior from Kingfield, was reading from a history textbook about the Civil War. He said the biggest difference between MSSM and other schools he has attended is that no one there is upset about having to do work.

“There is no encouragement of procrastination,” he said.

He likes the social environment more, too.

“It’s definitely not as cliquey,” he said.

Ashton Maze, a sophomore from Cumberland who is horizontal on a nearby couch, feels the same. He said middle school was rough for him, socially. When he got to MSSM, he saw a lot of people who looked like him.

“The idea that everyone here shares a lot of the same interests, that was attractive,” he said.

Maze said for him it’s not just that his classmates are all smart, which they are, it’s that they’re highly motivated, too.

“Everyone is working on these side projects that don’t have anything to do with school,” he said.

Hyejun Jung, a senior, is one of the 13 students who came from outside Maine. She lives in Pennsylvania but spent most of her childhood in South Korea.

The biggest difference for her has been how small the class sizes are and how much time she gets to interact with her teachers.

There was a culture shock for her, though.

“There isn’t much going on in Limestone,” she said with a laugh. “But I think that’s good. It keeps people focused. When there’s a foot of snow on the ground, what are you going to do but stay in and study?”

***

Emily Stillion typifies the kind of drive MSSM students have. The sophomore from Scarborough is constantly in motion. She’s involved in everything, from student senate to Key Club to the prom committee.

She also is often asked to give tours to prospective students and accompanied a reporter through the student dormitory. The dorm used to be the town’s elementary school, long ago when a lot more people lived there because of the Air Force base. It has four wings – two female and two male – and common areas where students meet after long days to play video games or watch movies.

Stillion’s dorm room, which she shares with another student, is impeccably neat and clean. The rooms on the boys’ wings, not so much.

Anna Foo, a senior from Cumberland, is involved in almost everything at the school. One of her favorite things is something called “the positivity box.” Students are encouraged to write compliments about their classmates and leave them in the box. Sometimes they are signed; sometimes they remain anonymous.

At the end of the week, the notes are distributed.

“It’s nice to be able to read these notes if you’re homesick or if you’re having a bad day,” Foo said.

The family atmosphere extends to faculty as well. They all live on campus, so they are around all the time. Meyer and Smith have had students over to their house.

“I couldn’t believe how much academic support there was here,” said Julianna Hundley, a sophomore. “There are office hours all the time and tutors, and you can even find teachers at night or on the weekends to help.”

Hundley grew up in southern Maine and attended Bonny Eagle Middle School in Buxton. She moved to Presque Isle before high school because she was placed with a new foster family. She did her freshman year at Presque Isle and heard about MSSM from a foster parent.

Hundley said the social environment has been surprising, too.

“Being around these people all the time, I think really makes us close,” she said.

***

The students don’t seem to care much about the school’s newfound status as the No. 2 high school in the country. MSSM has been in the top 20 of U.S. News and World Report’s rankings before. Besides, the organization is not the sole authority on academics.

But they don’t mind the attention either.

“This might be the only way people hear about us,” said Ethan Kelley, the junior from Yarmouth.

Rachel O’Brien. who graduated in 2007 and heads the school’s alumni organization, said graduates often scatter for college and their careers. Many end up in high tech areas like Silicon Valley. She lives in Vermont and works as a clinical case manager for a mental heath agency that supports seven school districts there.

When she attended MSSM, it was open only to juniors and seniors. She started there as a junior after spending her first two years of high school in Biddeford.

“I definitely credit a lot of my success as an adult to MSSM,” said O’Brien, who went on to Unity College. “I’m not sure I would have been as prepared for life.”

O’Brien, like many other alumni, has become an ambassador for the school, which she said still flies under the radar even though it’s almost a quarter century old.

“There is a mystery to it,” she said. “Even today when I tell people where I went to high school, they don’t really know what to say.”

But she felt pride to see MSSM get any recognition and would recommend it to any student who feels like they don’t quite fit in where they are now.

“I still have so many friendships,” she said. “I probably have a couch to stay on in all 50 states.”

There are a lot of inside jokes about penguins, the school’s mascot. The flightless birds are often seen as the oddballs of the natural world, and that’s how most of the students view themselves, too.

“We were all just a bunch of misfits who ended up in the same place,” O’Brien said.