HUNTER, N.Y. — For better or for worse, the third graders in Greg Fletcher’s class at Hunter Elementary School always know where they stand.

One morning in mid-October, Mr. Fletcher walked to the front of the classroom where an interactive white board displayed ClassDojo, a behavior-tracking app that lets teachers award points or subtract them based on a student’s conduct. On the board was a virtual classroom showing each student’s name, a cartoon avatar and the student’s scores so far that week.

“I’m going to have to take a point for no math homework,” Mr. Fletcher said to a blond boy in a striped shirt and then clicked on the boy’s avatar, a googly-eyed green monster, and subtracted a point.

The program emitted a disappointed pong sound, audible to the whole class — and sent a notice to the child’s parents if they had signed up for an account on the service.