Classroom Timer — Countdown, Pomodoro and Stopwatch

How to use the classroom timer

Pick Countdown, Pomodoro or Stopwatch from the switch at the top of the widget, set a duration or preset, then press Start. To keep the timer visible while you switch to slides, a PDF, or another browser tab, use “Keep on top” – it pops the timer into its own small window that floats above everything else on your screen. Everything runs from your own browser; nothing is uploaded anywhere.

What each control does

• Countdown / Pomodoro / Stopwatch – switches the timer’s mode. Each remembers its own settings.
• Preset chips (Countdown only) – quick durations from 5 to 60 minutes; click one before pressing Start.
• Label – an optional note (e.g. “Silent reading” or “Group discussion”) shown under the digits and mirrored in the browser tab title.
• Start / Pause / Resume – runs or pauses the current timer. Pausing freezes the remaining time exactly; it does not lose track of it.
• Reset – returns the current mode to its starting point. It does not change your saved settings.
• Lap (Stopwatch only) – records a split without stopping the clock.
• Keep on top – pops the timer into a small always-on-top window (Chrome and Edge 130+, and Firefox 151+ on desktop). On Safari desktop, iPad and iPhone it falls back to a display-only floating video window instead, since Safari does not support interactive pop-out windows for web pages. If neither is available, a draggable floating panel stays on top of this page instead – honest degradation, not a broken button.
• Fullscreen – large, high-contrast digits for a projector or a shared screen. Some embedded contexts (for example certain iframes) do not allow fullscreen; the widget will tell you rather than sit there doing nothing.
• Settings – alarm sound (with a “test sound” button), volume, light/dark theme, phase-change announcements for screen readers, and the three Pomodoro durations.
• Copy link – copies a link to this exact timer (mode, duration and label) so you can paste it into Google Classroom or share it with a colleague.
• + 1 min / + 5 min / − 1 min – adjusts a running or paused timer without losing the session. The ring stays proportional, and the alarm is re-set to the new finish time. Subtraction stops at five seconds, so it can never fire the alarm instantly. These buttons also appear in the pop-out window and in fullscreen, which is where you usually are when a class needs two more minutes.
• Warning before the end (Settings) – a single soft note at 30 seconds, 1, 2 or 5 minutes before time is up. Quieter and shorter than the end alarm, for giving a “two minutes left” instruction without stopping the room.
• Chime during the timer (Settings) – a soft note every 2, 3, 5 or 10 minutes. Built for station rotations, timed writing bursts and gallery walks.
• Colour the ring as time runs out (Settings) – the ring turns amber with a fifth of the time left and a brighter alert colour with a tenth left, then pulses in the final ten seconds. Silent, so it works in a room with the sound off. The pulse is suppressed if your device asks for reduced motion.
• Repeat alarm until dismissed (Settings) – repeats the end alarm every ten seconds for up to two minutes, until you press anything. For when you have walked to the other side of the room.
• Loud alert (Settings, alarm sound) – a harsher, longer alarm for noisy rooms. The other three are deliberately gentle.
• Round counter (Pomodoro) – shows “Round 2 of 4” under the phase, with a dot per round filling as you go.
• Stop after N rounds (Pomodoro) – ends the session cleanly after a set number of work rounds instead of cycling forever. Leave it at 0 to keep going.
• Start next phase automatically (Pomodoro) – on by default. Turn it off if you would rather click into each break and each work block yourself.
• Sequence – a chain of named steps, each with its own length, that runs straight through with a chime between each one. Pick a ready-made chain or build your own, then share the whole chain as a single link.
• Show seconds above 10 minutes (Settings) – turn off to show whole minutes during long stretches, so the digits stop twitching during silent work. The last ten minutes always show seconds.
• Ticking sound (Settings) – off by default. Some people want it for exam practice; most will not.
• Text size (Fullscreen, A− / A+) – makes the digits bigger or smaller for the room you are actually in.
• Copy all laps (Stopwatch) – copies the whole lap table, ready to paste into a sheet.
• Copy for Google Classroom – copies a labelled line rather than a bare URL, so it reads as something when you paste it into an assignment or announcement.
• Shortcuts – opens the full keyboard shortcut list. ? does the same thing.

Keyboard shortcuts

Every one of these works on the page, in fullscreen and in the pop-out window. Press ? at any time to see the list without leaving the timer.

• Space – start, pause or resume
• R – reset the current mode
• P – pop out, or bring back
• F – fullscreen
• ↑ or + – add a minute
• ↓ or − – take a minute off
• Shift with either arrow – five minutes at a time
• L – lap, in Stopwatch
• Esc – close a panel, or leave fullscreen

Sequence timer: chain the steps of a lesson

Most classroom activities are not one block of time, they are three. Think–Pair–Share is two minutes, then four, then six. A station rotation is the same five minutes repeated. Running those on a single timer means resetting it between every step, in front of the class, and losing thirty seconds each time you do.

Sequence mode runs the whole chain. Each step has its own name and its own length, a chime marks each change, and the dial shows which step you are on — “Step 2 of 3 · Pair”. Pick one of the ready-made chains below or build your own, then use Copy link to share the entire sequence as one URL.

• Think–Pair–Share – 2 / 4 / 6 minutes.
• Station rotation – four stations of 5 minutes, with a chime to rotate.
• Gallery walk – three viewing rounds of 3 minutes and a 5-minute debrief.
• Exam practice – a single 40-minute block; pair it with the warning chime for 10, 5 and 1-minute calls.
• Presentation + Q&A – 8 minutes then 4, so the questions do not eat the talk.
• Brainstorm–Cluster–Vote – 5 / 5 / 3 minutes.

Pomodoro: the 25/5 method in one minute

The Pomodoro Technique is a time-management method: work in focused 25-minute blocks, take a 5-minute break, and after every four blocks take a longer 15-minute break. The short breaks protect concentration; the long break prevents burnout across a study session.

Ways teachers use it

• Timing lesson transitions between activities without losing the class’s attention to a phone.
• Silent reading or independent work blocks, with the label showing what students should be doing.
• Exam-style practice under real time pressure, popped out and visible while you circulate the room.
• Group discussion or station rotations, with a short chime marking each rotation.
• Pack-up warnings before the end of a lesson.
• Keeping presentations and student talks inside their allotted time, projected in fullscreen mode.

Ways students use it

• Pomodoro revision sessions – 25 minutes on, 5 minutes off, with a long break every fourth round.
• Enforcing break discipline so a “quick break” does not become the rest of the evening.
• Timed past-paper practice under exam conditions.
• A stopwatch with laps for timing rehearsals or presentation run-throughs.

Embed this timer on your own site

Free to use and free to embed. No attribution required — but a link back is appreciated, and the snippet below already includes one, so there is nothing for you to add.

<iframe src="https://jonathanseet.net/educator/tools/classroom-timer/?chromeless=1" width="360" height="680" style="border:0" title="Classroom Timer"></iframe>

360 × 680 fits the timer with its controls at a phone-ish width. Go wider than about 760 pixels and the dial sits beside the buttons instead of above them, so you can drop the height to around 420. The embed is deliberately lean: it carries the timer, the three modes and the add-a-minute buttons, and leaves settings, sequences and round goals to this page.

Where teachers usually paste this. In Google Sites, use Insert → Embed → Embed code. In Notion, paste the URL on its own line and choose Create embed. In Canva, use the Embed app and paste the URL. Moodle, Canvas and Blackboard all accept the iframe in any HTML or rich-text block. If a platform strips iframes, link to the timer instead — it opens full screen on any device.

FAQ

Does the timer keep running if I switch to another tab?

Yes. The timer works out how much time is left from the clock, not by counting down a fixed number of steps, so it finishes on time and the alarm still sounds even if the browser tab has been in the background for a while.

Why does “Keep on top” look different on my phone or on Safari?

Only Chrome, Edge and Firefox on desktop currently support pop-out windows for ordinary web pages. Safari and mobile browsers do not, so the timer falls back to a display-only floating video window on Safari, or a floating panel on this page everywhere else. This is a genuine browser limitation, not a bug in the timer.

Is anything saved or sent anywhere?

Your preferences (sound, volume, theme, Pomodoro durations) and a timer’s label are stored in your own browser’s local storage so they are there next time you visit. Nothing is ever sent to a server.

What happens if I accidentally refresh the page?

If a timer was running or paused, you will see a “Resume timer?” banner with the time that was left, so a refresh does not cost you the session.

Can I share a preset timer with my students?

Yes – use “Copy link” to copy a URL that opens this page directly into the mode, duration and label you have set up, ready to paste into Google Classroom or a lesson plan.

Can I embed this timer on another site?

Yes – add ?chromeless=1 to the page URL for a chrome-free version suitable for an iframe. See the embed snippet below.

Will the alarm still play if my laptop goes to sleep?

If the deadline passes while the computer is asleep, the timer shows the correct finished state as soon as you wake it, rather than a stale countdown. The alarm itself needs the tab to be open and the computer awake to be heard, the same as any browser-based timer.

Can I add time to a timer that is already running?

Yes. Use + 1 min, + 5 min or u2212 1 min while the timer runs or is paused. The finish time moves, the progress ring stays proportional, and the alarm is re-set to the new finish time. You can also press the up and down arrow keys, or hold Shift with them for five minutes at a time. The buttons are in the pop-out window and in fullscreen too.

Can I run a Thinku2013Pairu2013Share or a station rotation on one timer?

Yes, that is what Sequence mode is for. Pick a ready-made chain or build your own named steps, and the timer runs the whole thing with a chime between each step and a step counter on the dial. Copy link shares the entire chain as a single URL.

Can it warn the class before time is up?

Three ways, and you can use them together. A single soft warning note at 30 seconds, 1, 2 or 5 minutes before the end. A repeating chime every few minutes for rotations. And a silent one: the ring turns amber with a fifth of the time left and a brighter alert colour with a tenth left, which works in a room with the sound off.

Print the Pomodoro study planner

A one-page planner for students running Pomodoro sessions: four rounds, what you intend to do in each, and what actually happened. Print it, or open it and save as PDF. Open the planner.

I build these because I train and teach this work — I am an adjunct lecturer at Singapore Polytechnic and I run copywriting and communication workshops for companies. If that is useful to you, here is what I do commercially.

Your preferences and any timer label are stored in your own browser, never sent to a server.