MIAMI — The bullying that bus monitor Karen Klein ­endured on a ride home from an upstate New York school was painful and egregious, but also shows how student harassment of teachers and administrators has become more spiteful and damaging in the online era.

Much attention has been paid to students who bully students in class, after school, and on the Internet. Less has been given to equally disturbing ­behavior by students who ­harass instructors, principals, and other adults.