“We have students so concerned about their privacy that they’re resorting to covering their [laptop] cameras and microphones with tape,” a junior said at the October 18, 2018 meeting.

It was another sleepy board of education meeting in Woodbridge, N.J. The board gave out student commendations and presented budget requests. Parents complained about mold in classrooms. Then, a pair of high schoolers stepped up to the podium with a concern that took the district officials completely off guard.

The companies that make this software—popular brands include Securly, Gaggle, and Bark—say that their machine learning detection systems keep students safe from themselves and away from harmful online content. Some vendors claim to have prevented school shootings and intervened to save thousands of suicidal children.

The capabilities of software programs like GoGuardian vary, but most can monitor the user’s browsing history , social media activity, and location, and some even log keystrokes. That surveillance doesn’t stop at the school doors, but continues everywhere children carry their school-issued computers and whenever they log into school accounts.

After a pause, board president Jonathan Triebwasser responded: “A very fair question. I don’t know enough about GoGuardian to give you a fair answer.” He asked the district’s superintendent to look into it.

“We just want to ask again: How are you going to assure our right to privacy when we have been having these problems and we have so many fears because of GoGuardian, and the fact that they can monitor everything that we see and we do?” the student asked the school board.

Woodbridge had recently joined hundreds of other school districts across the country in subscribing to GoGuardian, one of a growing number of school-focused surveillance companies. Promising to promote school safety and stop mass shootings, these companies sell tools that give administrators, teachers, and in some cases parents, the ability to snoop on every action students take on school-issued devices.

Bark says that its free monitoring software for schools protects more than 4 million children. Its tools have “prevented” 16 school shootings and detected more than 20,000 “severe self-harm” threats, according to the company’s homepage. From January through August 2018 alone, Bark claims, it identified five bomb and shooting threats, nine instances of online predators contacting children, 135,984 instances of cyberbullying, 309,299 instances of students using school accounts to talk about or buy drugs, 11,548 instances of children expressing desires to harm themselves or commit suicide, and 199,236 instances of children sharing explicit content.

School spying software has spread quickly as districts have increasingly put personal laptops and tablets in the hands of students. Meanwhile, school officials are under intense pressure to protect their wards from explicit online content and, even more urgently, detect early signs of potential school shootings.

“I’m sure there are some instances in which these tools might have worked, but I haven’t seen the data and I can’t verify in any way that what they’re saying is correct, or that there weren’t other ways available to get that information without subjecting the entire school to that surveillance,” said Faiza Patel, director of the Brennan Center for Justice’s liberty and national security program, who researches surveillance software.

The few published studies looking into the impacts of these tools indicate that they may have the opposite effect, breaking down trust relationships within schools and discouraging adolescents from reaching out for help—particularly those in minority and LGBTQ communities, who are far more likely to seek help online.

Numbers like that are understandably convincing to district administrators and parents, especially when companies offer their products to schools for free. Bark spokeswoman Janelle Dickerson said Bark makes its money from the $9-per-month version of its tool that it sells to families. The paid version currently covers 200,000 children, a small fraction of the 4 million children watched by the free version in schools.. Securly offers a paid premium product with more features than its free tool. Both companies categorically denied profiting from the data they collect on millions of students through their free offerings.

Upon closer inspection, the numbers Bark touts for its school software appear much more like marketing copy than legitimate data.

For one thing, the company’s numbers don’t always appear to be consistent. Earlier this year, Bark told TV stations in North Carolina and South Carolina that from May 2018 to May 2019, it had identified 14,671 instances of students expressing desires to harm themselves or commit suicide in those states alone.

When compared to the national statistics on its website, that would mean that the two states—which include just 50 of the more than 1,200 K-12 districts Bark claims as customers—produced a huge proportion of the incidents Bark flags across all 50 states.