On Saturday, thousands of people nationwide commemorated the 20th anniversary of the Columbine High School massacre in Littleton, Colorado, in which two shooters killed 13 people and themselves. And in the two decades since, schools around the country have continued to be targets of such tragedies — shootings at Marjory Stoneman Douglas High School in Florida, Sandy Hook Elementary in Connecticut and Santa Fe High School in Texas are among some of the deadliest incidents to have rocked schools and communities.

Columbine marked the beginning of what some now deem an "era of school shootings," with an average of 10 occurring each year in the U.S. It also marked the beginning of a new wave of protocol by schools — school resource officers, greater calls for mental health services and debates surrounding arming teachers — as a means of protecting students. Meanwhile, policymakers, educators and other stakeholders are still searching for answers to the problem.

With the recent landmark anniversary, we've compiled a list of our school safety-related coverage below that can aid administrators and educators in their efforts to keep students safe.

• Safety commission recommends armed school personnel, expanded mental health services: But most districts can't afford the solutions highlighted in the report without additional funding, says AASA, The School Superintendents Association.
• Building design a critical component in preventing school shootings: School violence affects communities nationwide, but addressing it requires carefully weighing the need for a welcoming environment with safety.
• Aspen Institute: SEL integration moves US from 'nation at risk' to one 'at hope': After a two-year process, the institute’s National Commission on Social, Emotional and Academic Development outlines a series of “conditions to enable good practice."
• School resource officers need SEL training, experts say — but their preparation 'lacks consistency' : SROs versed in social-emotional capacities are found to have a positive effect on schools. Now, more states want to require training.
• Parkland, Newtown suicides reveal 'systemic' lack of mental health supports: Health and school safety experts say the apparent suicides of two student survivors and a shooting victim's parent are a glaring sign things must change.
• AERA '19: Gaps between research, policy persist on gun violence prevention: In a town hall session, researchers called for attention to school safety issues beyond guns.
• RAND will help lead foundation-funded gun violence research effort: Educators will be among the groups participating on an advisory committee, along with healthcare professionals, university researchers, and representatives from government, law enforcement and the private sector.