messaging for a 7 year old

[onedayatatime73]

My 7 year old has an iPod and is desperate to be able to text me. Is there a messaging 'system' she can use on an iPod. Obviously I will monitor this and it's only me she would be allowed to message. At the moment she is 'texting' via dp email (however that works?) and would rather it wasn't linked that way.