Change between metric units of length, mass, capacity, area and volume, work with hours and minutes, and use scale drawings and map scales.
What you will learn
- Convert metric units of length, mass and capacity
- Convert area and volume units, including cm³ to litres
- Change between hours, minutes and decimal hours
- Use scale drawings and map scales written as 1 : n
Multiply going down, divide going up
10 mm = 1 cm 100 cm = 1 m 1000 m = 1 km
1000 g = 1 kg 1000 kg = 1 tonne
10 ml = 1 cl 100 cl = 1 litre 1000 ml = 1 litre
Changing to a smaller unit gives a bigger number, so multiply: 3.4 km = 3.4 × 1000 = 3400 m. Changing to a bigger unit gives a smaller number, so divide: 650 g = 650 ÷ 1000 = 0.65 kg.
To add or compare lengths given in different units, change them to the same unit first: 1.45 m + 62 cm = 145 cm + 62 cm = 207 cm.
Time is not decimal. 0.4 of an hour is 0.4 × 60 = 24 minutes, so 2.4 hours is 2 hours 24 minutes, not 2 hours 40 minutes. Going the other way, 135 minutes = 135 ÷ 60 = 2.25 hours.
The rest of this lesson and its 7 practice questions are locked.
In this lesson
- Multiply going down, divide going up
- Area and volume units: the mistake everyone makes
- Scales
- Try it: Check with the unit converter
7 practice questions, marked as you go; about 25 minutes in all.
Key terms
Smaller unit, Bigger unit, Area
In this unit: Ratio and proportion
Convert units and use scales, write and simplify ratios, share amounts in a ratio, compare best buys and exchange rates, and solve direct and inverse proportion problems.