After 13 people died in the 1999 shooting at Columbine High School, schools and law enforcement drastically changed how they react to school shootings.
In Ohio, it led to required training in school districts, but experts say doing the right kind of training is the key.
"This isn't about scaring you, it's not about making you paranoid, it's only about preparing you," Lakewood Police Officer and Swat Commander Pat Fiorilli told a room full of teachers and administrators.
The difference between a peaceful day at school and a deadly one can be small.
"Time is of the essence and these are over fairly quickly," said Lakewood Police Officer David Acklin. He is also a School Resource Officer in the Lakewood City School District.
Officer Acklin says active shooter and school emergency training has been around for a while. He's been doing A.L.I.C.E. training, standing for "Alert, Lockdown, Information, Counter, Escape," for almost five years.
"Our trainings through the years have changed from just presenting and talking about A.L.I.C.E. and now we get into the scenario-based format," said Officer Acklin.
The newer, hands-on training is intense and only started in the Lakewood School District last year, according to Lakewood's Safety Supervisor John Crane.
"Even in the highest profile shooter cases across the country, where teachers have had the opportunity to lockdown, shooters don't get access to those rooms," said school security expert Kenneth Trump.
Officer Acklin says his A.L.I.C.E. training allows people under attack to "counter," or fight back if it gets to that point, but it also encourages them to get out of the building if it's safe.
Better than just hearing about what's possible in a lecture, Ohio teachers are understanding what it's like to think critically when adrenaline is running high.
"We are empowering the students and the teachers to make decisions," said Officer Acklin.
Officer Acklin says the next step in introducing students to the same drills, possibly next school year. He says the challenge is doing it in a way that makes sense for each age level.
Other school districts around Cleveland tell us they're scheduling the testing they have to do as well. Each district we spoke to says they have their plans to meet state requirements that make them do some kind of training during the school year.