The city has introduced its first guidelines for the use of social media by teachers.
The Department of Education says teachers should refuse friend requests from students on their personal accounts on sites like Facebook and Twitter.
They're also being warned that their activity may be monitored and should have no expectation of privacy.
Teachers will be given training sessions on the new guidelines.
Education officials may also ask parents to sign consent forms before their children participate in social media activities or post their work online.