See every webpage they visit and how long they stay there
The tips for the internet
Websites for children are not permitted to request personal information without a parent's permission. Talk to children about what personal information is and why you should never give it to people online.
If children use chat or e-mail, talk to them about never meeting in person with anyone they first "met" online.
Talk to children about not responding to offensive or dangerous e-mail, chat, or other communications. Report any such communication to local law enforcement. Do not delete the offensive or dangerous e-mail; turn off the monitor, and contact local law enforcement.
Keep the computer in the family room or another open area of your home.