Perimeter

Test yourself

Perimeter

The perimeter of a shape is the 'outside' of the shape. You need to add all of the lengths of the shape.

Example 1

To find the perimeter of this shape, we need to add all the side lengths together.

Example 1 cont.

Example 2

To find the perimeter of this shape, we need to add all the side lengths.

Example 2 cont.

Missing length

Sometimes you might need to work out the missing length of a shape in order to find the perimeter.
What is the perimeter of the rectangle above?

Missing length

We use the information that rectangles have two pairs of sides of equal length to work out that the length of the missing side is 4 cm.

Perimeter of Composite Shapes

A composite shape can be made when two or more shapes are put together.

Example

This is a composite shape made up of two rectangles.

Perimeter of composite shapes

To find the perimeter. you must first work out the length of the missing sides.

Length of side a

To work out the length of side a, you need to look at how long the length of the shape is altogether.
- You can see that the longest verticle side is 6 m.
- You need to match with the other verticle side, which is 3 m long.
  - 3 m + ? = 6 m
  - So, side a is 3m long.

Length of side b

To work out the length of side b, you need to look at how long the two horizontal lengths are.
- The horizontal lengths are 4 m and 5 m.
  - 4 m + 5 m = 9 m
  - So, side b is 9 m long.

Calculating the perimeter

You can now calculate the perimeter by adding all the lengths on the 'outside' of the shape.

1Year 5 - Number

1.1Number & Place Value

1.1.1The Value of Digits to Millions

1.1.2Smallest & Biggest Numbers to Millions

1.1.3Ordering Numbers to Millions

1.1.4Counting in Powers of 10

1.1.5Counting in Negative Numbers

1.1.6Rounding Numbers up to 1,000,000

1.1.7Reading Roman Numerals

1.2Addition & Subtraction

1.2.1Written Methods for Adding Large Numbers

1.2.2Written Methods for Subtracting Large Numbers

1.2.3Mental Addition & Subtraction

1.2.4Rounding to Check Your Answer

1.3Multiplication & Division

1.3.1Multiples

1.3.2Factors

1.3.3Prime Numbers

1.3.4Prime Factors

1.3.5Composite Numbers

1.3.6Factor Trees

1.3.7Multiplication by a 1 Digit Number

1.3.8Long Multiplication Using Column Method

1.3.9Times Tables

1.3.10Division

1.3.11Multiplying & Dividing by 10, 100 & 1,000

1.3.12Square & Cube Numbers

1.4Fractions & Decimals

1.4.1Compare & Order Fractions

1.4.2Identifying Equivalent Fractions

1.4.3Add & Subtract Fractions

1.4.4Mixed Numbers & Improper Fractions

1.4.5Multiplying Fractions by Whole Numbers

1.4.6Converting Between Decimals & Fractions

1.4.7Rounding Decimals

1.4.8Ordering Decimals

2Year 5 - Measurement

2.1Measures

2.1.1Metric Measurements

2.1.2Imperial Measurements

2.2Perimeter & Area

2.2.1Perimeter

2.2.2Area

2.3Time

2.3.1Units of Time

3Year 5 - Geometry

3.1Properties of 3D Shapes

3.1.1Types of 3D Shapes

3.1.2Faces, Edges & Vertices

3.2Properties of 2D Shapes

3.2.1Polygons

3.3Angles

3.3.1Angles in Degrees

3.3.2Types of Angle

3.3.3Finding Missing Angles

3.4Position & Direction

3.4.1Reflection & Translation

4Year 5 - Statistics

4.1Graphs

4.1.1Line Graphs

4.1.2Tables

4.1.3Timetables

5Year 6 - Number

5.1Number & Place Value

5.1.1The Value of Digits to Ten Millions

5.1.2Ordering Numbers to Millions

5.1.3Rounding

5.1.4Negative Numbers

5.2Multiplication & Division

5.2.1Multiplication by a 2 Digit Number

5.2.2Division

5.2.3Multiples

5.2.4Factors

5.2.5Primes

5.3Mental Maths

5.3.1Multiplying & Dividing by 10, 100 & 1,000

5.3.2Addition & Subtraction

5.3.3Adding & Subtracting 10, 100 & 1,000

5.3.4Multiplication & Division

5.4Order of Operations

5.4.1BIDMAS

5.5Problem Solving

5.5.1Addition & Subtraction Multi-step Problems

5.5.2Problem Solving with Proportion

5.6Fractions & Decimals

5.6.1Simplifying Fractions Using Equivalents

5.6.2Ordering Different Types of Fraction

5.6.3Adding & Subtracting Fractions

5.6.4Adding & Subtracting Mixed Numbers

5.6.5Multiplying Fractions

5.6.6Dividing Fractions by Whole Numbers

5.6.7Converting Between Decimals & Fractions

5.6.8Dividing Decimals

6Year 6 - Ratio & Proportion

6.1Ratio

6.1.1Using Ratios

6.1.2Simplifying Ratios

6.2Percentages

6.2.1Calculating Percentages

6.3Scale

6.3.1Scale of 2D Shapes

7Year 6 - Algebra

7.1Sequences

7.1.1Describing Sequences

7.1.2Finding Gaps in Sequences

7.2Missing Number Problems

7.2.1Missing Number Problems

7.3Equations

7.3.1Balancing Equations

7.3.2Combining Two Variables

8Year 6 - Measurement

8.1Problem Solving

8.1.1Problem Solving with Measures

8.2Unit Conversion

8.2.1Conversion Between Miles & Kilometres

8.3Perimeter, Area & Volume

8.3.1Area

8.3.2Volume

8.3.3Nets

8.3.4Faces, Edges & Vertices

8.4Angles

8.4.1Types of Angle

8.4.2Finding Missing Angles

8.4.3Finding Missing Angles in Triangles

8.4.4Vertically Opposite Angles

8.5Circles

8.5.1Parts of a Circle

8.6Coordinate Grids

8.6.1Positions on Coordinate Grids

8.6.2Reflection & Translation

9Year 6 - Statistics

9.1Displaying Data

9.1.1Pie Charts

9.1.2Line Graphs

9.2Averages

9.2.1Mean

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