MEASUREMENT · TEXTBOOK LESSON
Measurement compares a quantity with a standard unit. Choosing suitable units and reading scales accurately are essential skills for length, mass, capacity, time and everyday problem solving.
Learning objectives
By the end of this lesson, you should be able to:
- Choose an appropriate unit for the quantity being measured.
- Read simple scales and measuring instruments accurately.
- Compare and order measurements.
- Convert between common units where appropriate.
1. Key vocabulary and definition
Definition
A measurement has both a numerical value and a unit, such as 12 cm or 3.5 kg. The unit tells us the standard quantity being used for comparison.
measureunitscalelengthmasscapacitytime
2. Essential facts and rules
These are the facts you should know before attempting the worked example.
Key mathematical facts
- 100 cm = 1 m.
- 1000 g = 1 kg.
- 1000 mL = 1 L.
- 60 seconds = 1 minute and 60 minutes = 1 hour.
3. Standard method
A reliable method helps prevent errors and makes your reasoning easy to follow.
1
Identify what is being measured.
2
Choose a sensible unit and instrument.
3
Read the scale from the correct starting point.
4
Record the value together with its unit.
5
Estimate first to check whether the measurement is reasonable.
4. Worked example
Worked example
A bottle contains 1.5 L of water. How many millilitres is this?
1
1 L = 1000 mL.
2
Multiply 1.5 by 1000.
3
1.5 × 1000 = 1500.
4
Therefore 1.5 L = 1500 mL.
5. Common mistakes
Watch out for these
- Starting calculations before deciding what the question is asking.
- Skipping important steps or changing notation midway through a solution.
- Accepting an answer without checking whether its size, sign or unit is sensible.
6. Video lesson
This topic is ready for a matching video lesson. The written textbook lesson is fully available now; additional videos can be added to the same lesson template.
7. Practice exercise
Complete these without looking at the answers first.
- Convert 3 m to centimetres.
- Convert 750 g to kilograms.
- Convert 2.4 L to millilitres.
- How many minutes are in 2.5 hours?
- Choose a sensible unit for the mass of a school bag.
Show answers
- 300 cm
- 0.75 kg
- 2400 mL
- 150 minutes
- kilograms (kg)
8. Chapter summary
- Understand the underlying idea before memorising a procedure.
- Use precise mathematical notation and show a logical method.
- Always check the final result.