There is an app called 'Dumbsmash' which is video messaging app where people can upload themselves singing over famous songs and then choose to share via whatsapp, facebook, instagram or via a text message. It is not intended for children under 18 and you must be 18 or 13 years or older with parents permission to use it. However there are some primary school children utilising this app.
There is also a question and answer site about the app where someone has asked whether or not they should upgrade to Dumbsmash 2. It says
'Dumbsmash 2 has nothing to do with Dumbsmash but is a malware app that hides itself on phones and then pushes users to porn sites. As soon as it is set up, the icon deletes itself and runs in the background without the users knowledge.' I would request that school’s alert parents to this and monitor what their children are accessing.