Schools Abroad Brace Against Terrorism

Worries Heightened by Killing in Russia

When Ardie Geldman was growing up in the West Rogers Park neighborhood on the north side of Chicago years ago, he and his classmates were routinely encouraged to pick up any trash cluttering the streets. It was their civic duty, as then-Mayor Richard J. Daley and the city’s omnipresent signs reminded them: Keep Chicago Clean!

These days, as an administrator for a network of elementary and secondary schools in Israel, Mr. Geldman offers starkly different advice to students who see a stray paper bag or an odd-looking piece of litter near any of their buildings: Avoid it and notify authorities immediately.

Those precautions, and others like them, have taken on renewed relevance for school officials in Israel and other countries in the weeks since a 52-hour hostage standoff at a school in southern Russia resulted in the deaths of more than 330 people, about...