A child can learn to tell the time on a clock fairly easily but mastering time calculations is a whole other ball game
It is very important to acknowledge that there is a HUGE difference between telling time, and working out what the time was 45 minutes ago.
Telling Time Ages 5 to 6
A child should be able to read the hour and half-hour marks on an analogue clock and be able to draw in the hands for example if you say “Draw three o’clock.”
Telling Time Ages 6 to 7
A child should know the number of seconds in a minute, minutes in an hour, hours in a day and days in a week. A child should also be able to understand quarter-to and quarter-past when read a clock or drawing the hands on a clock.
Telling Time Ages 7 to 8
A child should be able to also read digital clocks, understand AM and PM as well as the 24-hour clock (e.g. that 1PM = 13:00), and be able to use the associated vocabulary such as morning, afternoon, AM, PM, noon, midday and midnight etc.
Time Calculations for Ages 8+
Children age 8+ should be able to perform time calculations starting with simple sums such as “It is 8AM now, what will the time be one hour from now?” – continuing on to more complex questions for 9+ into years 5 and 6 using train timetables and working out how long it takes a train to go from one city to another.
AM / PM Time Calculations
More complex questions involve AM and PM – e.g. where the answer to a train timetable question overlaps from AM into PM and vice-versa.
24 Hour Calculations
This is the final level in KS2 which a lot of children struggle with, including into Secondary School (and including a lot of adults!).
Such questions involve adding and subtracting hours and minutes even across midnight into the next day, where answers must be expressed in 24hr clock notation.
For example a plane leaving London at 8:05PM which takes seven and a half hours to fly to New York. What time will it arrive in London time and New York time, expressing both answers in 24hr notation including the day.
This is not easy and requires a better method than just using clock faces.