The tablets, made of polyethylene fiber and weighing just three pounds (1.5 kilograms), have been in the classrooms of Worcester Preparatory School in historic Berlin, Maryland since 2013.
Berlin, which features a population of 5,000 and is located just miles from some popular Atlantic beaches, calls itself "America's coolest small town."
The prep school's whiteboards, measuring some 20 by 18 inches (50 by 45 centimeters), look like those used in many classroom around the country. But with handles screwed to their backs, they are designed to allow a teacher like Bragg to protect herself from an assailant's bullets.
The whiteboards are produced not far from Berlin by a small company, Hardwire, which has become a world leader in bullet-resistant equipment and armored devices, sold both to American police departments and the US Army.
Shocked by the 2012 massacre at Sandy Hook Elementary School in Newtown, Connecticut, where a young shooter killed 26 people -- including 20 six- and seven-year-old children -- Hardwire's boss, George Tunis, saw a way to help out while moving into a new market: classrooms.
When a shooter entered a high school in Parkland, Florida on February 14 and began firing his assault rifle, the school's assistant football coach, Aaron Feis, was among the first of the 17 victims to be gunned down as he attempted to protect students from the gunfire.
- 'A last, last resort' -
Tunis said he believes his company's shield "would have made a difference."
In addition to the protective whiteboards, Hardwire makes armored clip boards, tablets and notebooks. It also makes hardened inserts, the size of a notebook, that can be placed in a student's backpack.
The company equips schools in Maryland, Minnesota and Delaware, and exports outside the country as well.
It refuses to reveal its revenue figures but says that since the Parkland shooting, "sales have been skyrocketing."
Prices range from $75 for a backpack insert to $1,000 for a whiteboard capable of stopping rounds from an assault rifle.
"It's a last, last resort for personal protection," Tunis said.
At Worcester Prep, with 500 students from kindergarten through 12th grade, administrators, teachers and students' parents say they are fans of the whiteboards.
"Whiteboards have given our teachers a real comfort," said Barry Tull, 72, who is in his 33rd year as Worcester's headmaster.
Though some teachers were initially "not at ease" with the idea, "as they trained to use this as one more piece of security, they got very comfortable," he said.
Many Berlin residents support the whiteboards.
"It's a good start," said Jessica Collins, 34, a local police officer. "They're taking very good protective measures."
- Armed teachers? 'Nuts' -
And Gretchen Spraul, mother of a first grader, called it "a huge comfort level for all the parents."
Some in this rural town also say they would favor having teachers carry guns, as suggested by President Donald Trump.
Tull, who is set to retire at the end of the school year, admits he is "not too crazy" about the idea of arming teachers. "At the same time, I'm not totally opposed to it if it were done in the right way... I don't turn every idea away."
Bragg, for her part, is resolutely opposed.
"I personally don't want to shoot a gun," she said. "I am not a very big person. I am 100 pounds (45 kilograms), so someone could easily overtake me" and take her gun. "It would cause more harm than good."
Spraul suggested she might support a carefully organized plan to arm some teachers.
"How extreme do we have to get?" she asked thoughtfully, before adding, "Never say never."
"That would be wonderful if teachers knew how to have self-defense," Spraul said. "But don't just hand out pistols!"
But to Tunis, the Hardwire chairman, putting guns in schools would be "nuts."
"Just imagine, I'm a teacher, I shot at a shooter, miss him and hit a student. What's your mental state? What do you do now?"