Forty-six minutes gives a forty-five a minute to open and close the books without stealing from the lesson. Use the edges for logistics and the middle for the actual thinking.
Say that out loud. Otherwise the logistics spread until the thinking is a rumor. 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 46 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 46 minutes timer on a projector?
Press start, then F or the fullscreen button. Classroom mode hides the writing so the digits fill the wall. Say that out loud. Otherwise the logistics spread until the thinking is a rumor.
What is 46 minutes actually good for?
Forty-six minutes gives a forty-five a minute to open and close the books without stealing from the lesson.
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.