Before his freshman year at the University of Connecticut, J.T. Lewis received an unusual gift from his mother: a bulletproof backpack.

Mr. Lewis, who will be a sophomore at the university, comes from a family shattered by gun violence: His younger brother, Jesse, was killed in the 2012 shooting at Sandy Hook Elementary School in Newtown, Conn. When his mother, Scarlett, gave him the dark-gray backpack, he said, she did not have to say a word.

“We just had a mutual understanding,” said Mr. Lewis, 19, who is running for a seat in the Connecticut State Senate.

Now he wears the armored backpack on campus because it makes him feel safer, even if it means he sweats a little more under the bulky load.