Stop Start

We also have an issue with the start button. It works fine, but if you click it more than ones, the function runs multiple times.
I.e. If you click it four times, you’ll get the first notification four times. The only plus with this is it makes you seem really popular because your phone keeps going off giving illusions of your phone receiving lots of text messages 
A lot of people did this as there is currently no overstate on the play button. I think the best way to stop people from pressing the button multiple times would be to create a start state and a stop state. Once the button is pressed the app goes into 'Study Mode' and the play button is replaced by a stop button. This way you can only send the notifications once and then notifications could be stopped when you leave study mode. The switching of states and changing of the button will be easy enough but stopping the notifications when the button is pressed will present more of a challenge.