It's so easy to forget to silence your phone when you're late for class, or early for that matter. Help yourself be a better student.
If
Connects to a specific WiFi network
This Trigger fires every time your Android device connects to a WiFi network you specify.
Then
Mute ringtone
This action will mute your Android device's ringtone. If your device is already muted, it will remain muted.
Explore more great ways to automate Android Device and Android Device