Facebook is an incredibly dangerous tool if used by the wrong people. Facebook allows anyone to connect, regardless of whether they know them or not, which is a huge e-Safety issue for young children.
Facebook rules state that no persons under the age of 13 are allowed to have Facebook account. Therefore there shouldn't be any children who attend Gray's Farm that has one.
Below is the official guidance from Facebook regarding under-aged accounts on their site:
"Facebook requires everyone to be at least 13 years old before they can create an account (in some jurisdictions, this age limit may be higher). Creating an account with false info is a violation of our terms. This includes accounts registered on the behalf of someone under 13.
If your underage child created an account on Facebook, you can show them how to delete their account.
If you'd like to report an account belonging to someone under 13, please fill out this form. Note that we'll promptly delete the account of any child under the age of 13 that's reported to us through this form."
If your child has a Facebook account we strongly advise that you follow the above instructions to remove it from their system, likewise if you are aware of any other children with Facebook accounts who are under the age of 13 you can report these to Facebook for investigation.