Good idea, but this on its own may not be that successful. Modern private schools use a combination of Saas apps and email to get info to students and parents. What you need to do is to find out what those major Saas solutions are, and get in bed with them. Also, there is a potential problem if the student replies to a text and replies to everyone that was texted to, which can happen easily on some devices, so it would seem that you'd want to ensure each text is separately sent.