Ten seconds is a cue, not a work block. Think photo pose, a breath, a 'hands up' in a noisy room. You will not switch tabs. You will watch it, which is why the digits are large.
Use a sharp beep. A soft chime is easy to miss in ten seconds of shuffling. Fullscreen and classroom mode are the projector tools. Classroom mode hides the article and the links so the digits take the wall. Turn it off from the same button. Keyboard shortcuts keep working: space, R, and F.
This page is the 10 seconds 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 seconds timer on a projector?
Press start, then F or the fullscreen button. Classroom mode hides the writing so the digits fill the wall. Use a sharp beep. A soft chime is easy to miss in ten seconds of shuffling.
What is 10 seconds actually good for?
Ten seconds is a cue, not a work block. Think photo pose, a breath, a 'hands up' in a noisy room.
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.