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In Key Stage 2 you extend your measurement skills to cover unit conversion, perimeter and area of different shapes, volume, and angle measurement. These skills connect directly to real life — building, cooking, travel, and design.
You need to know the common metric units and how to convert between them.
Length:
| Unit | Conversion |
|---|---|
| 10 mm | = 1 cm |
| 100 cm | = 1 m |
| 1,000 m | = 1 km |
Mass:
| Unit | Conversion |
|---|---|
| 1,000 g | = 1 kg |
| 1,000 kg | = 1 tonne |
Capacity:
| Unit | Conversion |
|---|---|
| 1,000 ml | = 1 litre |
| 100 cl | = 1 litre |
Examples:
Length unit ladder. Multiply going down (smaller unit), divide going up (larger unit):
flowchart TD
A[km] -->|x 1000| B[m]
B -->|x 100| C[cm]
C -->|x 10| D[mm]
D -->|/ 10| C
C -->|/ 100| B
B -->|/ 1000| A
Perimeter is the total distance around the outside of a shape.
Rectangle: P = 2l + 2w (or P = 2(l + w))
Irregular shape: add up all the sides.
Finding a missing side from a perimeter:
Area is the amount of space inside a 2D shape. It is measured in square units (cm^2, m^2).
Rectangle: Area = length x width
Triangle: Area = (base x height) / 2
Parallelogram: Area = base x height (again, perpendicular height)
Compound shapes: split into rectangles and triangles, find each area separately, then add them.
Volume is the amount of space inside a 3D shape. It is measured in cubic units (cm^3, m^3).
Cuboid: Volume = length x width x height
Counting cubes: you can also find volume by counting unit cubes that fill the shape.
Example: How many 1 cm^3 cubes fit in a box 6 cm x 2 cm x 5 cm?
An angle measures the amount of turn between two lines at a point. Angles are measured in degrees.
| Angle type | Size |
|---|---|
| Right angle | exactly 90 degrees |
| Acute angle | less than 90 degrees |
| Obtuse angle | between 90 and 180 degrees |
| Straight angle | exactly 180 degrees |
| Reflex angle | between 180 and 360 degrees |
| Full turn | 360 degrees |
Angles on a straight line add up to 180 degrees.
Angles around a point add up to 360 degrees.
Vertically opposite angles: When two straight lines cross, they form four angles. The two pairs of angles directly opposite each other are called vertically opposite — and they are always equal.
Using a protractor:
Money problems use the same addition, subtraction, multiplication, and division skills — just with £ and p.
Key facts:
Adding money:
Subtracting and giving change: To find change, subtract what you spent from what you paid.
Example: An item costs £4.65. You pay with £10. How much change do you get?
Example: You buy 3 items costing £1.20, £2.45, and £0.75. You pay with a £5 note.
Mixed units: Always convert everything to the same unit before calculating.
You also need to know approximate equivalences between metric and imperial units.
| Metric | Approximate imperial |
|---|---|
| 1 km | 5/8 of a mile (roughly 0.6 miles) |
| 1 m | about 39 inches (roughly 3.3 feet) |
| 2.5 cm | about 1 inch |
| 1 kg | about 2.2 pounds (lbs) |
| 1 litre | about 1.75 pints |
Tip: These are approximations — you won't need to convert exactly, but you should be able to say which is bigger and make rough estimates.
Miles and kilometres:
Examples using the 5:8 ratio:
Converting time units:
| Conversion | Value |
|---|---|
| 60 seconds | 1 min |
| 60 minutes | 1 hour |
| 24 hours | 1 day |
| 7 days | 1 week |
| 52 weeks | 1 year |
| 365 days | 1 year |
12-hour and 24-hour clock:
Time intervals:
Year 6 pupils are designing a rectangular school garden that is 8 m long and 5 m wide. They need to calculate the perimeter (for fencing), the area (for turf), and the cost. Turf costs £4.50 per square metre and fencing costs £6.20 per metre.
Step 1 — Calculate the perimeter.
P = 2l + 2w = 2 x 8 + 2 x 5 = 16 + 10 = **26 m**
Step 2 — Calculate the area.
A = l x w = 8 x 5 = **40 m²**
Step 3 — Calculate the fencing cost. A gate of 1 m is needed, so only 25 m of fencing is required.
Fencing cost = 25 x £6.20 = **£155.00**
Use long multiplication: 25 x 6 = 150; 25 x 0.2 = 5; total 155.
Step 4 — Calculate the turf cost.
Turf cost = 40 x £4.50 = **£180.00**
Use 40 x 4 = 160; 40 x 0.5 = 20; total 180.
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