Ten minutes is a presentation run-through, an oven check, or a guided pause that still fits between classes. It is the longest timer most people will watch without starting a second activity. Use that.
Speak a talk once at this length and you will hear where it drags. The alarm is a kinder editor than a clock on the wall. Press space to start or pause, R to reset, and F for fullscreen. The screen can stay awake after you start, using the wake lock your browser allows. Pick the alarm before you begin. A bell, a chime, a beep, or a short digital pulse all come from the Web Audio API, so there is no sound file to wait on.
This page is the 10 minutes countdown and nothing else is running underneath it. Related lengths are linked under the guide if you want a neighbor, and the timer itself stays above the fold.
Questions
How do I run a 10 minutes timer on a projector?
Press start, then F or the fullscreen button. Classroom mode hides the writing so the digits fill the wall. Speak a talk once at this length and you will hear where it drags. The alarm is a kinder editor than a clock on the wall.
What is 10 minutes actually good for?
Ten minutes is a presentation run-through, an oven check, or a guided pause that still fits between classes.
Will the countdown drift if I switch tabs?
No. The end is a timestamp. The display is the gap between that timestamp and now, so a background tab does not lose seconds the way a ticking counter would.