The American Federation of Teachers and National Education Association joined with the advocacy group Everytown for Gun Safety Support Fund in calling for an end to unannounced drills or drills that simulate gun violence.

“Everywhere I travel, I hear from parents and educators about active shooter drills terrifying students, leaving them unable to concentrate in the classroom and unable to sleep at night,” said Lily Eskelsen Garcia, president of the National Education Association. “So traumatizing students as we work to keep students safe from gun violence is not the answer. That is why if schools are going to do drills, they need to take steps to ensure the drills do more good than harm.”

Active shooter drills have become more common as more school massacres have made headlines. But there is hardly any research on the drills’ effectiveness, and while there are some federal recommendations, there is no standard template for schools to follow in terms of how to do them, how often to conduct them and how to explain them to students of different ages.