When training a class or delivering a long workshop, it is always difficult to get people to come back to their desks in due time.
The same happens when assigning a test to be completed within a specified time. Missing a common shared timer for everyone, it gets a little difficult to communicate efficiently to everyone when time is really running out.
In these situations, what can work extremely well, is the use of a digital countdown timer to be projected on the main audience screen. In this way, you need not continuously interrupt or distract attendees to inform them of the remaining time and anyone can see at a glance how much time is left.
Here PowerPoint expert and book-writer Ellen Finkelstein gives a step-by-step tutorial on how to build such a digital countdown clock.