HARI SREENIVASAN:

Over the generations there has always been some type of school drill. During the Cold War, there were duck and cover drills, in different parts of the country today there are tornado earthquake drills but a more common occurrence today is a school lockdown driven by gun violence and mass shootings.

I recently spoke with Washington Post reporter John Woodrow Cox, co-author of a groundbreaking analysis examining how many children are impacted by these lockdowns and what some of the consequences are.