I would monitor communication when your kids begin to go online—some do as young as 7 and 8—and are on sites that have interaction (like chatting, for example.) Also, cell phones can be used to cyberbully, so the answer is really when kids begin to use online communication tools. Talk to them about using these tools responsibly and respectfully, and lay down some ground rules for the kind of behavior you expect. Explain, too, that if they see some bullying, they should talk to you about it. Hopefully, you may never have to worry about it—but keep an eye on the devices that they use to communicate with other kids to make sure that everything is in accordance with your expectations.
Information provided by Caroline Knorr, Parenting Editor of Common Sense Media. For more tips about teaching your kids to be safe online, visit Common Sense Media