clipped from: www.nytimes.com   

Katherine Evans said she was frustrated with her English teacher for ignoring her pleas for help with assignments and a brusque reproach when she missed class to attend a school blood drive.

So Ms. Evans, who was then a high school senior and honor student, logged onto the networking site Facebook and wrote a rant against the teacher, Sarah Phelps.

A few days later, Ms. Evans removed the post from her Facebook page and went about the business of preparing for graduation and studying journalism in the fall.

But two months after her online venting, Ms. Evans was called into the principal’s office and was told she was being suspended for “cyberbullying,” a blemish on her record that she said she feared could keep her from getting into graduate schools or landing her dream job.

You can express an opinion on whether someone is a good teacher,
“But when you start inviting people to say that they hate a teacher, that crosses the line.”