The Petersburg School District recently purchased a less invasive way than a breathalyzer to test for alcohol, coming after a few students were hospitalized amid the homecoming dance in February.

The Passive Alcohol Sensor appears to be a black flashlight. On the side, though, is a sensor that reads alcohol levels. Petersburg school staff members can administer the alcohol sensor simply by asking a student to say his or her name into the small hole on the side, said Richard Dormer, the middle and high school principal, at a school board meeting on Tuesday.

Jaime Cabral, the athletic direct...