How to time an exam: start, finish, reading time and extra time

Most timing problems in an exam room come from arithmetic done in a hurry. The paper starts four minutes late, someone works out a new finish time in their head, and the board and the clock disagree for the next two hours. The way to avoid it is to make one moment, the actual start, the source of every other time.

What candidates need to see

1. The start time, as it happened.
2. The finish time, which they plan against. “I need to be on question 4 by ten past” is a thought about the finish time, not about minutes remaining.
3. The time remaining, which the invigilator needs for announcements and nervous candidates like to check.

A wall clock gives only the current time and leaves each candidate to subtract. A countdown alone gives no finish time to plan against. Show all three.

Start when the paper starts

Whatever the timetable says, the duration runs from the moment candidates are told to begin. If a two-hour paper scheduled for 9:00 begins at 9:04, it ends at 11:04.

The exam clock works this way. You set the length, press start when the paper begins, and it writes the start and finish times from that moment, so what is on screen always agrees with itself. Press F for fullscreen and project it; the fullscreen view is the clock alone, with no ads. Add a label, such as the room or the paper, if several rooms are running at once.

Reading time

Some papers give a reading period before writing starts. It is not taken out of the writing time. Run it as its own countdown, clearly labelled, and begin the writing time at full length when it ends.

In the exam clock, turn on a reading period and it counts that first, labelled as reading time, then moves into writing time by itself. Candidates can see which phase they are in without asking.

Extra time

Extra time is a percentage of the paper’s length, most often 25%. Work it out before the day, not during the paper.

Paper length	25% extra	New total
45 minutes	11 min 15 s	56 min 15 s
1 hour	15 min	1 h 15 min
1 hour 30	22 min 30 s	1 h 52 min 30 s
2 hours	30 min	2 h 30 min
2 hours 30	37 min 30 s	3 h 7 min 30 s
3 hours	45 min	3 h 45 min

If the whole room has the allowance, set the clock to the new total. If one candidate has it, write that candidate’s finish time on a card on their desk, and run a second clock for them in another browser tab or on another device. One clock shows one finish time.

If something interrupts the paper, such as a fire alarm or a candidate taken ill, note the time lost and add it back. The exam clock lets you add minutes while it runs, and the finish time on screen moves with it.

Announcements

Exam boards set their own rules for when invigilators speak, and those rules come first. Where you have a choice, as in a class test or a mock, two announcements are enough: one at thirty minutes remaining and one at five. More than that breaks concentration more than it helps.

Check the room before anyone sits down

• Project the clock and walk to the furthest desk. If you cannot read the finish time from there, enlarge it before the candidates arrive.
• Plug the laptop in and close anything that might show a notification over the clock.
• The page asks the browser to keep the screen awake while the clock runs. The time itself comes from the system clock, so even if the machine did sleep, the time remaining would be right when it woke.

Mock exams at home

Everything above applies to one person at a kitchen table. Use the real duration. Put the clock where you can see it without picking up a phone. Stop when it stops. Pacing is a skill, and the only way to practise it is against a real finish time.

To know what you should have done by each point, work out a plan first. The exam time calculator shares the time out by marks and gives each section a finish-by time; minutes per mark explains the arithmetic, and how to split a 3-hour exam works it through for two CBSE papers.

For timing lessons and group work, where the clock needs to be friendlier, see classroom activity timings.