Use the Timer and Automatically Lock Student Screens
You can set a timer so students know how much time they have left to answer a question. When the timer reaches zero, the student screens will automatically lock.
The timer is a part of the lock button on your navigation bar. If you click the lock button once, student screens will lock and they won't be able to change their answer on the current slide. If you hold down the lock button, you will be able to start a timer before the screen locks.
How to Lock a Slide
1. While displaying an interactive slide, click the lock button once.
Voilà! The student screens are locked.
How to Set the Timer on a Slide
1. While displaying an interactive slide, click and hold the lock button on the navigation bar to engage the timer.
2. Set it for 30 seconds, one minute, or three minutes.
3. The timer will begin counting down. Here is the student's screen. The student can clearly see that she has 40 seconds left to answer the question...
...You will also be able to see the countdown on the Projector View. As the timer gets close to zero the color changes to red:
4. When the timer hits zero, student screens will automatically lock so they can no longer respond.
5. If you want to give students more time, simply click the lock button again, OR press and hold it again to reset the timer.