No teacher should need to be told not to have inappropriate relationships with students - in real life or electronically.

No school district should need to have a policy detailing what is and what isn't appropriate communication between teachers and students. Improper behavior should be obvious.

But unfortunately, some teachers do need to be told. School districts do need to have policies. And Gov. Chris Christie should sign a bill, approved by the Legislature last week, that would require districts to institute such policies.

Inappropriate teacher-student relationships, of course, are not new. But modern electronic communication - social media, cellphones, etc. - have made such improper behavior easier. And making it easier for people to do wrong is always dangerous.

"The number of school personnel having inappropriate contact with students has been just exploding all across the country," state Sen. Diane Allen, R-Burlington, a sponsor of the bill, told The Star-Ledger. "... It's social media that's really to blame. There's just so many ways school personnel can contact and have relationships with students."

The bill, S441, would require districts to adopt policies designed to prevent improper communications between school employees and students via email, cellphones, social-networking sites and other Internet-based media.

Some districts have such policies, but most don't. Those districts would have four months from the bill's signing to write guidelines.

A word of caution: The guidelines should be sensible. They shouldn't be so strict that they prevent all electronic communication between teachers and students. Social media and online communication will be playing an increasing role in the educational process - allowing classes to be conducted during days when schools are closed because of weather, for example.

And some school policies do go too far. Pennsville, for example, forbids teachers from giving out their private phone numbers without prior approval. We're not sure that's necessary.

The New Jersey School Boards Association has a sample policy for districts to use. That would be a good starting point.

In the end, the problem of improper relationships between teachers and students is a character issue, not a policy issue. No policy will stop someone intent on doing wrong.

But everyone - schools, teachers, students and parents - would benefit from guidelines that make clear what is and isn't acceptable.

At least then, no teacher - especially young teachers who never knew a world without Facebook or texting - could claim that he or she didn't know where the line is between acceptable and unacceptable behavior.