[arin-ppml] Continuation: Policy Change Request: IP Address Assignment to Educational and Non-Commercial Organizations
As has already been pointed out by others on the list, even were you to obtain an IP address range from ARIN or some other entity it would do you no good without the cooperation of your local ISP. Your ISP would need to route/advertise that IP address in order for you to have any connectivity to it.
IF your project is legitimate and you are unable for whatever reason to get a static IP address assignment from your ISP might I suggest a simpler solution for your project might be to get authorization of funds from your school-board (or community organization) to rent a Virtual Private Server at a reputable hosting company (you may even find one willing to provide a discount for educational institutions) and use that as a point of connection. You could then install VPN software on that hosted server that supports PPTP connections and use private address space over those tunnels for connectivity with your peer classrooms.
You may run into some complications with FW's or conflicting private address space that you have to work out but it'll probably be an easier route for you.