Thirty-seven minutes is a prime block for one ugly draft or one careful reading. You will want to split it. Don't. The value is staying with the same page.
When it ends, stand up before you check a message. The stand-up is the break, not the inbox. 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 37 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 37 minutes timer on a projector?
Press start, then F or the fullscreen button. Classroom mode hides the writing so the digits fill the wall. When it ends, stand up before you check a message. The stand-up is the break, not the inbox.
What is 37 minutes actually good for?
Thirty-seven minutes is a prime block for one ugly draft or one careful reading.
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.