The Next Web reported yesterday, you can now simply type into Google search "set timer" followed by an amount of time and a countdown timer is displayed. An alarm beeps when time is up. You can make the timer appear full screen without advertisements by clicking a little box icon to the right of the timer. You can see this feature in action in the video below.
Applications for Education
Whenever I have long blocks of instructional time I like to break it up with short breaks and or timed hands-on activities. One tool that can help to prevent the students and me from stretching the "break times" is to use a countdown timer like this one.