Hi, I am a professor of mathematics in chile and I really like your application.
Unfortunately in practice, with students can not be used.
In exams, they could be cheating using whatsapp or request help through the mail.
Is possible to add these features to activate a "Teacher Mode":
1.- Phone in Airplane Mode automatically.
2.- Open default ROM.
3.- Application Foreground.
4.- Block or disable notification bar and physical buttons. (available only the button back)
5.- finally, to activate the "Teacher mode" immediately enter a 4 digit passcode to exit the application. (key that would assign the teacher to exit the application with button back).
These features allow many teachers use your program and not just chile, also the rest of the world.
That would be unique.