Chapter 6: Measurement, Time, and Money
Measurement, Time, Money and Unit Rates
Choose the correct unit, calculate carefully, and explain what each answer means.
AI teacher
Press Start to hear a short classroom-style explanation. If sound is unavailable, the full script is shown below.
Voice: Browser voice
Workbook pages
Fun Maths Book 2 pages 78-90
Work with perimeter, area, elapsed time, timetables, money and unit rates.
AI explanation
The AI teacher compares length, area, time and money as real-life measurements. It shows why perimeter is around a shape, area is the space inside, and elapsed time is the gap between two times.
- 1Perimeter means the total distance around the outside.
- 2Area means the amount of surface covered.
- 3Elapsed time is found by counting on in sensible jumps.
- 4A unit rate tells the cost or amount for one item.
Think with the AI teacher
Today maths will feel practical. We will measure around, inside, across time, and for one item.
Question 1
Pause 4sWhen finding perimeter, are we measuring around the outside or filling the inside?
After thinking
Perimeter measures the distance around the outside.
Yes. Your finger can trace the perimeter.
Question 2
Pause 5sHow could you find elapsed time without rushing?
After thinking
Count on in friendly jumps, such as hours first, then minutes.
Excellent strategy. Friendly jumps reduce mistakes.
Question 3
Pause 4sIf 3 notebooks cost $12, what does unit rate ask for?
After thinking
It asks for the cost of one notebook.
Great. Unit means one.
Deep structure
What children discover
Children discover that units describe what the number means, so a measurement answer is incomplete without the correct unit.
Common mistake
Children may find area when the question asks for perimeter, or forget the unit in the final answer.
Future connection
Measurement foundations support compound shapes, speed, density, scale drawings, trigonometry and real-world modelling.
Animated demonstration
See the maths move
A shape outline lights up for perimeter, square tiles fill the inside for area, and a clock timeline jumps through elapsed-time steps.
Guided examples
Perimeter
A rectangle is 12 cm long and 7 cm wide. Find its perimeter.
- 1.Perimeter is all sides added.
- 2.A rectangle has two lengths and two widths.
- 3.Calculate 12 + 7 + 12 + 7.
Elapsed time
A lesson starts at 10:35 am and lasts 1 hour 45 minutes. What time does it finish?
- 1.Add 1 hour: 10:35 am becomes 11:35 am.
- 2.Add 25 minutes to reach 12:00 noon.
- 3.Add the remaining 20 minutes.
Interactive practice
Try it now
Before calculating, circle the unit in the question and write whether the answer is length, area, time or money.
Which unit is sensible for the length of a classroom?
Find the area of a 9 cm by 6 cm rectangle.
3 notebooks cost $12. What is the cost of 1 notebook?
Review
Point to the outside of a shape for perimeter and the inside for area.
Parent signal
Check that units are included. A correct number without a unit is not yet a complete measurement answer.
Nice practical thinking. Your answer should always mean something in the real world.