Time and Clocks
Reading analog/digital time, elapsed time and 24-hour clocks.
Key idea
Reading analog/digital time, elapsed time and 24-hour clocks.
In depth
Time uses base 60 for minutes and seconds and base 24 for hours, so decimals and carrying do not work like base ten. Elapsed time is a subtraction in these units; clocks are cyclic.
Worked example
From 9:45 to 1:20 pm: 9:45 to 12:45 is 3 h, then 35 more minutes, total 3 h 35 min.
Real-world uses
- Planning a timetable
- Calculating travel time across time zones
- Reading 24-hour railway and airline schedules
Common mistake
Treating 1.5 hours as 1 hour 50 minutes. It is 1 hour 30 minutes.
How to learn this
- Read the key idea and say it in your own words.
- Work through the worked example, then try a similar problem.
- Use the interactive lesson’s visual and mini-quiz to check the pattern.
Frequently asked questions
What is Time and Clocks?
Reading analog/digital time, elapsed time and 24-hour clocks. It is a topic at the beginner level in Arithmetic & Number Sense.
Where is Time and Clocks used in real life?
Real-world examples: Planning a timetable; Calculating travel time across time zones; Reading 24-hour railway and airline schedules.
What should I learn before Time and Clocks?
Make sure you are comfortable with Length, Mass and Capacity, the previous topic in Arithmetic & Number Sense.
What is a common mistake with Time and Clocks?
Treating 1.5 hours as 1 hour 50 minutes. It is 1 hour 30 minutes.
How can I practise Time and Clocks?
Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.
What comes after Time and Clocks?
Move on to Money Arithmetic next.
Related beginner topics in Arithmetic & Number Sense
- Counting & Cardinality – Assigning one number word to each object to find how many there are.
- Place Value – The value of a digit depends on its position: ones, tens, hundreds and so on.
- Number Line – A line where numbers are placed in order at equal spacing to compare and add them.
- Comparing Numbers – Use <, > and = to say which number is smaller, larger or equal.
- Ordering Numbers – Arranging numbers from least to greatest or the reverse.
- Even and Odd Numbers – Even numbers divide by 2 with no remainder; odd numbers leave remainder 1.