Perhaps the candidates who showed up to Wednesday’s mayoral forum in a Harlem school auditorium thought they’d get a break when they saw who was asking the questions: a couple of high school kids.

But Michael Cummings and Alize-Jazel Smith, seniors at Democracy Prep Charter High School, turned out to be tough moderators. They shushed Bill Thompson when he spoke out of turn, politely interrupted Comptroller John Liu when his time was up, and pushed candidates to answer the questions they were asked if they had strayed off topic — as one candidate did often.

“So, Mr. McMillan, just to be specific,” said Cummings, referring to Jimmy McMillan, the perennial also-ran candidate of the Rent Is Too Damn High party. “Do you support or do you not support co-location inside school buildings for public schools and charter schools?”

McMillan, last seen running for governor against Andrew Cuomo in 2010, used up his two minutes suggesting he would decentralize the school system, upgrade technology, and replace school curriculum — but not actually answering the question.

“If they benefit from learning, yes,” McMillan said of co-locations. “But if it doesn’t, no.”

In addition to education, the forum also covered issues about public safety, housing, and jobs. It was organized and hosted by Democracy Builders, a parent advocacy group that is part of the Democracy Prep Public Schools, and the crowd consisted mostly of students from the charter school network.

McMillan, Liu, and Thompson were joined on stage by Sal Albanese after two other candidates — Public Advocate Bill de Blasio and Adolfo Carrión, Jr. — canceled their appearances. Liu and Thompson arrived late because they had been at a teachers union forum in Brooklyn.

Several Democracy Prep charter schools share space in public school buildings through co-location, a controversial practice that several candidates have vowed to stop. Speaking for the first time directly with charter school students, the candidates were encouraging but did not abandon their positions.

“I think it’s a disservice to the students, whether they be in schools that were already in that school building or whether they be in the schools that are entering that building,” Liu said about co-location.

Liu left early, but Thompson arrived in time for a “lightning round,” where Smith asked the candidates yes or no questions. Thompson at one point complained that the format wasn’t allowing him to articulate his views..

“The only thing I need to say to everybody is, in the lightening round the questions aren’t simple yes, nos,” Thompson said after Smith asked him if standardized testing was an effective measure of student learning. “They’re very involved, so when you talk about issues of co-location, when you talk about standardized testing — does standardized testing count? — sure. Is it the only measure of student achievement? Absolutely not.”

Jimmy McMillanVID00876 from GothamSchools on Vimeo.