Classroom Tools for Teachers

Timers for classrooms

Timers and classrooms go together because a visible countdown does the managing for you: it makes the length of a task explicit, it ends an activity without anyone being told off, and it turns "two more minutes" from a negotiation into a fact on the wall. Edutopia makes the case at length in Embracing Classroom Timers.

Select a preset timer below, or create a custom timer for any other length.

Want students looking forward to the timer rather than dreading it? A Touch of Class Teaching has a good round-up of ways to make them fun: how to use classroom fun timers to your advantage.

On the projector

Both tools have a full-screen mode, which is the point at which a timer becomes readable from the back of a room: the digits fill the display and everything else gets out of the way. The countdown also appears in the browser tab title, so a teacher watching a laptop can see the time left without switching tabs.

The alarm clock is the one to use for a fixed moment rather than a duration — the end of a test, the start of an assembly — and its full-screen bedside mode doubles as a classroom wall clock.

Keyboard control, so you're not hunting for a button

The multi-timer board on the main timer page is click-only — the shortcuts are on the single-duration pages, which is where you want them mid-lesson anyway.

Transitions, rotations and routines

The timer runs up to three countdowns at once, each with its own label and its own alarm sound. That is enough for a three-station rotation where every group is on a different clock, and the different sounds mean a group knows their time is up without looking.

Common uses that map straight onto the presets above: a two-minute tidy-up, a five-minute warm-up, a ten-minute station, fifteen minutes of silent reading. There is also a study timer for longer focus blocks.

Reading fluency, repeated timings and experiments

This is what the stopwatch's lap button is for. Tap Lap at the end of each reader, each attempt or each trial, and you get a numbered list where every row shows two things: the lap time (how long that one took) and the total (elapsed time since you started). The fastest lap is highlighted green, the slowest red, and the fastest, slowest and average are shown above the list.

For repeated-trial work — a pendulum, a reaction test, a timed run — that means one session gives you every trial and the spread, without stopping and restarting between them.

Sharing what you measured

A measurement nobody can keep isn't much use in a classroom, so the stopwatch lets a session leave the page two ways:

The CSV is the one for records: a row per stopwatch — its name, a column for each lap, then the total — so three groups are three rows you can read down, and a term's sessions stack in one sheet instead of fighting over the lap numbering. A timing with no laps is simply the name and the time. The image is the one for people, and it is what you want to hand a student, drop into a report, or send to a colleague or a parent.

Both files are named for the date and time you saved them, followed by the names of any stopwatches you renamed — 2026-08-08-1615-group-a-group-b.csv. A folder of them sorts itself into the order the lessons happened, and no two ever overwrite each other.

Nothing is uploaded. The session — including a stopwatch still running — is stored on that computer, so it survives a refresh, and the CSV and the image are made in the browser.

Science: the sun, the moon and the solar system

Two simulators, both free, both running entirely in the browser, and both built so the picture never claims more than it can show. Each carries its own lesson plan and a scale card that says exactly how wrong the drawing is — which is usually the most useful twenty minutes in the room.

Sun, Earth & Moon movement simulator

The Earth seen from above its orbit, with your own town marked on it, the half of the planet in daylight, and the moon at its true angle from the sun. Drag through a day, a week or a month, or press Play.

• Why we have day and night — a day span and Play: the Earth turns and the marker rides in and out of the lit half, while the sun does not move at all.
• Why the moon has phases — a month span, watching the moon–sun angle and the phase disc together. 0° new, 90° quarter, 180° full. Nothing covers the moon up.
• Why summer days are longer — the same city on 21 June and 21 December: watch the axis lean and how much of the daily circle falls in the light.
• The midnight sun — a far-northern city in June, where the daily circle never leaves the daylight.
• Tidal locking — why the same face always points at us, and why “the dark side of the moon” is a misnomer.

There is a page for every city with a sunrise page, so you can start from wherever the class actually is. Location, date, time and span are all in the link, so one URL puts thirty screens on the same sky.

Solar system simulator

The planets on their real orbits, with a slider over a month, a year, a decade or a century, and a zoom that climbs from the Earth and Moon out to Neptune.

• How empty space is — the Earth & Moon view is to scale in size and distance at once, which is why, across a 900-pixel frame, the Earth is a dot 14 pixels wide and the moon under 4. Almost every diagram a student has seen is wrong about this.
• Why the solar system won't fit on a screen — zoom out to Neptune and Mercury's entire orbit is 7 pixels across. The four inner planets become one labelled knot, which is the truth that evenly-spaced textbook diagrams hide.
• How differently the planets move — press Play on a year: Mercury laps four times, Earth once, Neptune barely twitches. A century still isn't one Neptune orbit.

Off-screen follow-up, and the one students remember: shrink the Earth to a 16 mm marble and walk the class down the corridor. The moon is a 4.4 mm bead — a peppercorn — 48 cm back; the sun is a 1.7 metre ball, taller than you, 188 metres away.

What a browser timer can't do

Worth knowing before a lesson depends on it:

• It rings only while the page is open. The tab can be in the background and the window can be behind another, but if the tab is closed or the machine sleeps, no alarm.
• A background tab may be updated less often by the browser, so a display that isn't on screen can lag.
• The precision you see depends on the device and browser. Good for everyday use — not for official sports timing, scientific measurement or anything medical.
• Sound needs the device's volume up and, on some browsers, one tap on the page first before audio is allowed to play. Test it once on the classroom machine.

Running stations? Six stopwatches on one screen lets each group have its own — named, and coloured so a group can find its card from across the room — and exports them side by side.

The full browser limitations page explains why, the measured accuracy figures show how far off a browser timer actually is, and how it works covers the timing itself.

Accessibility — what to check

Stated plainly, because a classroom is exactly where this matters:

• The big read-out is drawn as segments rather than text, so it also carries a text version for screen readers. It is deliberately not announced on every tick — a display that spoke every second would be unusable — which means a screen-reader user gets the value on demand, not a live countdown.
• At zero the timer does three visual things as well as ring: the read-out turns to the accent colour and flashes, Time's up! appears under it, and the tab title changes — so a deaf or hard-of-hearing student watching the projector gets the same signal at the same moment. What it does not do is vibrate, and the flashing is the display itself rather than the whole screen, so it needs to be visible: on a projector, full-screen it.
• Every control is a real button and reachable by keyboard, and the shortcuts above work without a mouse.
• The display colour can be changed on the alarm clock and the timer if the default is hard to read on your projector.