Many 12-15 year olds have access to the internet which cannot be supervised by an adult.
discuss the problems that this might cause.

There are many problems that might cause.  One, children might go on illegal websites such as inappropriate sites and gambling sites.  Facebook is also illegal for children under the age of 14 but many still can fake their age.  Another problem is that kids might accidentally or purposefully give out personal information which could lead to cyberbullying, hacking, or even terrorizing.