Everyweek, you have a meeting, class, or an exam on a specific time of a day. Does it bother you to take out your phone every time and turn it to silent mode, and turn it back to normal at the end of the meeting? There is a big chance you will forget to do that.
The best suggestion is to manage you android gadget to switch to silent mode on specific times of the day.
Download and install ZDbox right now and go to the "Do Not Disturb" section of the app.
Now choose the exact date and time you want your gadget to be silent on. You will never be disturbed again.