Peter Vogel introduced me to an online timer that will be my go-to timer from here on. The Teachit Timer is a free online timer that allows you display a countdown timer and a count-up timer on the same screen. The Teachit Timer also allows you to choose an alarm sound.
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 Teachit Timer.