Telling the Time and Reading Timetables

El método, paso a paso

1. 1

   Read an analogue clock in two parts

   short hand → hours · long hand → minutes

   The minute hand moves five minutes for each number on the face, so pointing at 3 means fifteen minutes past. Reading the hands separately, hours first, prevents the confusion of treating both as pointing to the same scale.

2. 2

   Convert between 12-hour and 24-hour time

   3:45 pm → 15:45 · 09:20 → 9:20 am

   Add 12 to the hours for any pm time after noon. Midnight is 00:00 and noon is 12:00, which are the two cases students most often get the wrong way round.

3. 3

   Find a duration by counting on

   09:40 to 11:15 → 20 min to 10:00, 1 hr to 11:00, 15 min → 1 hr 35 min

   Count up to the next whole hour, then in whole hours, then the remaining minutes. Subtracting the times directly as if they were decimals gives 1.75, which is not the answer.

4. 4

   Read a timetable column by column

   each column is one service; each row is one stop

   Follow a single column downwards to trace one journey, and read across a row to compare when different services reach the same stop. Reading in the wrong direction is the main source of error.

5. 5

   Watch for services that skip stops

   a dash or blank means that service does not stop there

   Not every service calls at every stop, so the fastest journey is not always the next departure. Questions are frequently built around exactly this, and the blanks are easy to read past.

Time does not work in tens

Every other measurement a child meets works in tens: centimetres to metres, grams to kilograms, pounds to pence. Time works in sixties, and treating it as decimal produces answers that look reasonable and are wrong.

The error appears most often on calculators. Entering 1.45 for one hour forty-five minutes and getting a plausible result is a routine mistake, and it is why time calculations should be done by counting on rather than by subtraction.

• 60 seconds in a minute, 60 minutes in an hour
• 1.5 hours = 1 hour 30 minutes
• pm times: add 12 for 24-hour clock
• Midnight 00:00, noon 12:00
• Find durations by counting on, not subtracting

Why counting on is more reliable

Working out a duration by counting up to the next hour, then across whole hours, then the remaining minutes, avoids borrowing across a base-60 boundary entirely. It is slower to write and considerably harder to get wrong.

It also handles journeys that cross midnight without special treatment, which direct subtraction does not. Counting from 23:40 to 00:25 is straightforward; subtracting them is not.

What timetable questions really test

These questions test careful reading more than arithmetic. Which column, which row, whether a service stops at all, and whether the question asks for the arrival time or the journey length are the four places marks are lost.

They are also genuinely useful. A student who can compare two services and work out which arrives first has a skill they will use, which is not true of every topic in the curriculum.

How we teach time

We teach counting on as the standard method for durations and discourage subtraction entirely at this stage. The base-60 borrowing is where the errors live, and the counting method sidesteps it.

We use real timetables rather than simplified ones, including services that skip stops. Cleaned-up examples remove exactly the feature that the exam questions are built around.