I still dont understand exactly what you are trying to ''sell'' but i understand that you might be trying to protect your idea with some vagueness. In view of the above i can say the following. 1. Use facebook connect and allow users to post their activities on their wall (not automatically though because you'll be banned)
2. Target 2 schools close to each other and ensure scholars in those schools use whatever it is you ''selling''
3.Get inside info on the popular kids in that school and pay them to use your app for a month or 2.