It was one year ago that a former student opened fire at Marjory Stoneman Douglas High School in Parkland, Fla., killing 17 students and staff members. Since then, schools have scrambled to boost security- securing buildings, adding surveillance cameras and police officers. Some argue there’s a lower cost, less intrusive measure that can help prevent school violence - encouraging students to report threats or other safety concerns to an anonymous tip line. Colorado started its statewide tip line after the Columbine shooting 20 years ago. The idea picked up after the Sandy Hook tragedy in 2012, and now, in the wake of Parkland, have taken off. The latest state to join this effort is Pennsylvania, where a new tip line has received thousands of tips in just the first month of operation. We take a look at how the effort is going, and whether tip lines work.