It’s an act of ingenuity set against a backdrop of gruesome US school shootings. A conservative calculation by The Washington Post (paywall) found that more than 150,000 students in at least 170 schools in America have experienced a campus shooting since the Columbine High School attack in 1999. While politicians squabble—seemingly endlessly—over stricter gun control measures, some students are focusing on finding quick and easy ways to secure and strengthen locked school doors.

It can mean the difference between life and death. Experts say shooters may not force their way past locked doors, seeking easier targets.

At Benjamin Banneker Academic High School in Washington, DC, students created a similar device. Sold for $15, the metal DeadStop can be clasped around the hydraulic arms at the tops of many classroom doors. The students were awarded a $10,000 grant by the Lemelson-MIT Student Prize program to develop the invention further. They also got pro-bono representation from a law firm to file for a patent.

A similar invention was created by a handful of middle-school teachers in Muscatine, Iowa. Following the December 2012 mass shooting at Sandy Hook Elementary School in Connecticut, the teachers designed and created a 12-gauge carbon-steel case called “The Sleeve” that is also attached to a door’s hydraulic arm.

Each of those devices are designed to be heavy-duty door locks—but students are also being armed with rudimentary tools. Shocked by the most recent massacre, at Parkland’s Marjory Stonemason Douglas High School in South Florida, a Connecticut woman posted on Facebook about giving her nieces rubber door stoppers to keep in their backpacks in case of a shooting.

“If a gunman shoots out the door lock it will still keep the door from opening and may just buy you some time,” she wrote in her Facebook post, which has gotten more than 1.3 million shares.

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