Teacher can use the Timer feature to do a Countdown or use as a Stopwatch.
To use the Timer...
click the Timer button on any screen where you see it. For example, on the Students and Send screens.
The timer will open, choose Countdown or Stopwatch, set time if needed and click Start
If using a Countdown, an alarm will sound when the countdown reaches 0.
Note: You can close the Timer dialog and any active timer you have will continue. If using a countdown, when it reaches 0, the Timer dialog will open and a sound will play.