The young people who experienced the recent school shooting in Parkland, Florida, were born in or after 1999. In that year, two students killed 13 classmates at Columbine High School in Colorado. Since then, the United States has had six more of the 10 deadliest school shootings in its history. Along with those events, there have been smaller, less publicized acts of gun violence on campuses. The Washington Post newspaper found that, since 1999, more than 150,000 children have experienced a shooting at their school. The Post reporters note that those numbers are conservative. They do not include suicides or accidents with guns that happen at school, or shootings that happen after classes have ended. In other words, today’s high school students have been raised at a time when school shootings in the U.S. have become common. The cumulative effect of this gun-related school violence may help explain the recent protests by young people.