Designing a social network for children using an ece based application I have built

I have designed an online software programme that allows teachers to write and store children's profile books online. A profile book is a book that holds all the learning of a child who attends a childcare setting from the age of 0-5. This is normally in paper form but I am hoping this will move steadily online as more of our life does. I had an idea about linking a social aspect into the website to be used on iPhones, etc plus also through the website. My vision would be that children who use this application would be able to communicate with other children at the centre through the development of a social media aspect, such as facebook but really on a much smaller scale. I would image that they would be able to only friend other people in the same centre and we need to remember we are dealing with 3,4,5 years with the possibility of it being used to maintain contact with their friends once they leave the childcare centre. Their might also be the possibility of this being able to stand on it on. Ultimately what I desire is to create a safe and secure way children can communicate with each other. Within the application I would imagine the children being able to create an avatar for them self. Any ideas, thoughts, and help would be great