I think this would be a very handy tool to have in the classroom - a Simple Timer . This timer can be used two ways. One, as a countdown timer for an activity that you want to keep to a certain period of time. Second, you could use this clock to time a certain event or activity. The Simple Timer can be projected onto a screen or onto an Interactive Whiteboard so that everyone knows how much time is left or how much time they are taking to perform a task.
I learned about the Simple Timer from one of my favorite blogs ILearn Technology.