"It is safe and easy to sign up for. You can contact 8 people at once in one call."
- it's easy for a child aged 11 to register.
"There are lots of layers to the signing process, you must have a Gmail account, but there are lots of extra choices which could expose more personal information if you don't choose to skip each one."
We asked parents of 8-12 year olds how easy it would be for an 11 year old child to pretend to be a different age to sign up, and whether any checks were in place.