EGLIN AIR FORCE BASE, Fla. — Four students gathered near several cluster munitions stuck nose-down into the ground. They were conferring on how best to flip over a piece of air-dropped dispenser without risking injury from any unseen bomblets hidden underneath. (This was soon done with a rope and shovel, together forming a lever that a student could pull from afar.)

A few miles away, several students clutched watches while testing a green strand of time fuze. They were clocking the rate at which it burned so they could set up a precisely timed demolition later in the morning.

In a third patch of forest, Pvt. Kevin A. Stanley, 20, crouched with Airman First Class Joshua P. Oliver, 21, and studied a temporary mystery: the precise identification of a shell that had failed to explode. Was it Russian? Bulgarian? White phosphorous? High explosive? Something else?

Image Despite its name and location, the school serves four military services. This year, officers say, it will train 1,800 people. Credit... The New York Times

The projectile body was rusted, but the underside of its fuze still carried metal stampings in Cyrillic. The men crawled forward with instruments resembling dental mirrors, trying to read the unfamiliar letters without touching the round and possibly causing it to burst.