For an hour on Thursday morning, the auditorium at Lakeville North High School turned into a courtroom.

There were real lawyers, real Minnesota Supreme Court justices and a real case. There were also, in rows of stadium seats, about 600 real high school students listening in.

“This is a serious case,” Justice Natalie Hudson told the crowd after hearing oral arguments. “This was a courtroom as far as the seven of us are concerned.”

Twice a year since 1995, the Supreme Court has heard a case at a school in one of the state’s 10 judicial districts. Cases are chosen based on how well-argued they’re expected to be, how accessible the subject matter is and whether the attorneys agree to the change of venue.

On Thursday, the case was State of Minnesota v. David Lee Haywood. It centers on whether a BB gun — in this case, one possessed by a felon — qualifies as a firearm. The court will now deliberate and deliver an opinion, a process that typically takes from three to five months.

Haywood, who was convicted on a felony drug charge in 2005, was found guilty of another felony after police found a BB gun in his car during a 2013 traffic stop. The appeals court upheld Haywood’s conviction, relying on a 1977 state Supreme Court case that included BB guns in the definition of “firearm” — which felons are prohibited from having.

For 60 minutes, the justices peppered attorneys Grant Gibeau and Thomas Ragatz — who represented Haywood and the state, respectively — with questions. Is the fact that Haywood’s BB gun looked like a real gun enough to call it a firearm? Should conflicting dictionary definitions of “firearm” be taken into account? And under existing definitions, would a felon be allowed to fire a starter pistol? Or a Taser? Or a Nerf gun?

“It was interesting. I enjoyed watching it,” said junior Lexie Stebbins, who participates in one of Lakeville North’s four mock trial teams and dreams of becoming a lawyer. She said Gibeau’s argument — which defined a firearm only as a weapon that discharges a shot using gunpowder — made the most sense to her.

Hearing a case at Lakeville North was particularly significant for Justice Christopher Dietzen, who plans to retire at the end of August. His two granddaughters, Haley and Anna Steel, are students there and were charged with showing him around Thursday afternoon.

Sitting together during lunch with the other justices and a group of mock trial participants, Dietzen said this was the first time members of his family had gotten to see him at work. His favorite part? Announcing his granddaughters’ names and having them stand up in front of all their classmates.

Hudson argued cases before the Supreme Court during her time in the Minnesota attorney general’s office, including some at schools. Though it could be nerve-racking as an attorney to look out and see a crowd of students, she said, this kind of outreach is important.

“Very few people see the inner workings of the appellate courts,” she said.

Once Thursday’s arguments were over, students got to turn the tables and ask the justices questions. Some were serious — What’s the interview process like to become a Supreme Court justice? How often do justices take the Constitution into account when deciding cases? What’s it like being a woman in the legal world? — others less so.

Justice Barry Anderson was asked if the justices ever hang out outside of work (no), Justice David Stras was asked his favorite movie (“Happy Gilmore”) and Justice Margaret Chutich offered up her favorite Disney princess (Mulan) to a roar of applause.

Near the end of the question-and-answer session, a student approached the microphone and asked the justices if they ever get bored.

“No,” Chief Justice Lorie Gildea responded. “Next question.”