Teachers like Sara Haskett feel the fear and the pain.
"I know that those students are my students," Haskett said.
Students feel it too.
"Schools are supposed to be a safe place, and it's really sad to say this but it's not," senior Kenji Breitenbucher said.
As the tragedy unfolded in Florida, leadership students at Manteca High School were putting up 1,600 Post-Its on lockers. One for each student.
The all featured positive statements -- "You matter", "Life is a beautiful thing", "You are worth it" -- spreading kindness as an antidote to violence across the country.
"Students might be going through the same thing that one kid was and they see these Post-It notes and they look on their locker and they've got such a nice note to read, makes them smile makes them change their whole perspective," Breitenbucher said.
The students understand that in a world of social media, cell phones and Emojis, words matter, kindness matters and it's contagious.
"Having a physical copy saying you're worth it, you're important," Breitenbucher said. "It's everything."