How to use the Classroom Stopwatch
- Start it. Press Space or the Start button. Press it again to pause, and once more to carry on.
- Record laps. Press L or Lap while it runs. Each lap shows its own time and the running total.
- Read the results. The fastest lap turns green and the slowest red. Press C to copy every lap and paste it into a spreadsheet.
- Start again. Press R or Reset to clear the time and the laps.
Classroom ideas
- PE and sports day: time each runner’s lap of the field, then compare the fastest and slowest laps with the class.
- Science experiments: time how long ice takes to melt, a pendulum’s ten swings, or a toy car down a ramp — repeat it and average the laps.
- Reaction times: one pupil starts the stopwatch, another stops it the moment they see it move. Who can get closest to exactly 5.00 seconds?
- Personal bests: time a times-table sprint or a tidy-up and challenge the class to beat it tomorrow.
- Show the dial on the Classroom Board so younger pupils can watch the second hand sweep round.
Keyboard shortcuts
| L | Record a lap |
| D | Switch between digits and the dial |
| C | Copy the laps |
| F | Present full screen |
Frequently asked questions
Does the stopwatch keep going if I reload the page?
Yes. It remembers when it was started, not a count, so a reload, a closed lid or a busy computer cannot make it drift. It shows the right time as soon as the page is back.
How accurate is it?
It reads your computer’s clock, so it is accurate to well under a hundredth of a second over hours. The display updates every screen refresh.
How do I get the lap times into a spreadsheet?
Press C or Copy laps, then paste into Excel or Google Sheets. Each lap comes out as a row with its number, lap time and total.
Can I hide the hundredths?
Yes. Turn off “Show hundredths of a second” in Settings for a calmer display that ticks once a second.
Is there a countdown version?
Yes — use the Classroom Timer to count down, or the 3D Sand Timer for a visual one.
Updated October 31, 2026 · Free to use in any classroom, no account needed.