On the morning of March 7, Rabbi Beth Naditch found out that two of her three children’s schools had received bomb threats. While the news was shocking, it was something she and her husband had made sure to discuss with their sons — ages 9, 12 and 14 — so they would be prepared.

The anonymous calls placed to the MetroWest Jewish Day School and the Solomon Schechter Day School in suburban Boston turned out to be hoaxes, like the rest of the calls placed to more than 100 Jewish institutions since January.

A week before, a relative of Naditch’s was evacuated from a JCC during another bomb threat wave. And as a rabbi at a Jewish elder care facility, she spoke regularly with Holocaust survivors or refugees who were feeling echoes of their pasts.

So Naditch and her husband spoke to their boys about anti-Semitism, why it’s returning and what to do if it reaches them.

“My husband and I were just waiting for it to hit our kids,” she said. “We were trying to walk a fine line between having them prepare and be aware of safety measures, aware that there are people in the world who want to hurt us or other people because they are anti-Semitic or racist, and trying not to terrorize them.”

The Boston-area campuses were two of at least 12 Jewish day schools that have received bomb threats since the beginning of the year. Most have targeted JCCs, largely affecting either adults who can process the distress or preschoolers too young to perceive it.

But the threats against Jewish schools have created uncertainty among parents, teachers and administrators. Many of the students are old enough to understand the threats, but not old enough to cope by themselves. Schools want to give enough information to answer their questions, but not enough to traumatize them. They want to explain anti-Semitism, but not normalize it.

“This is something we may do, but it’s not a fun thing, it’s not a good thing, it was an unfortunate thing that happened,” Rabbi-Cantor Scott Sokol, head of school at MetroWest Jewish Day School, told his students. “We’re not looking to make it a bigger deal than it was. At the same time, they understand this is something that happens more to kids at Jewish day schools.”

Many schools delivered their messages based on the grade level. Students up to third grade in some schools were told they were going on a fire drill. Fourth- and fifth-graders in several schools were told there was a threat, they were safe and little more. Middle schoolers and high schoolers, many of whom read the news on their own, were given a fuller picture.

But every school has placed limits on its communication. At MetroWest, Sokol asked students and parents not to post about the threat on social media. At the Hebrew Day School of Ann Arbor, Michigan, and Aleph Bet Jewish Day School in Annapolis, Maryland, both threatened on Feb. 27, administrators opted to give the students no more information than necessary.

“Talking that directly with our older students helped them understand, ‘OK, this was a threat. It’s no longer there,’” said Sarah White, head of school at Aleph Bet. “That was the only conversation we’ve had with them. At school, you’re expected to be safe. If things are organized, things are calm and teachers are in control, you feel safe.”

Administrators at various schools said that their top priority was to get students back in class and on schedule. Several returned to a regular school day following a brief evacuation. At the Charles E. Smith Jewish Day School outside Washington, D.C., which also was threatened on Feb. 27, high school principal Marc Lindner said police did not require the students to leave class.

“Our general approach was we wanted to keep things as normal as we possibly could,” Lindner said.

For teachers, the bomb threats have meant broaching anti-Semitism with children, sometimes before it appears in their curriculum. Several school officials said they have stressed how much support they have received from the community.

“They are taking what’s happening across the nation very personally,” said Allison Oakes, head of school at the Lerner Jewish Community Day School in Durham, North Carolina, which was threatened on Feb. 22. “We wanted to focus on, yes, this is happening in our world, but let’s take a look at everyone trying to support us.”