Year 6 - Maths
Explain how to calculate the area of a triangle
Area, perimeter, position and direction
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will explain how to calculate the area of a parallelogram and a triangle. They will describe the relationship between scale factors and side lengths. They will describe positions in all 4 quadrants.
Lesson Summary
You will learn to explain how to calculate the area of a triangle.
Key Notes
- The area of a triangle is half the area of a parallelogram with same base and perpendicular height.
- The area of a triangle can be calculated using the formula area = base × perpendicular height ÷ 2
Vocabulary To Learn
- Parallelogram: A parallelogram is a quadrilateral with two pairs of parallel and equal sides.
- Base: The base is the side which is perpendicular to the shape's height.
- Perpendicular: Two lines are perpendicular if they meet at a right angle.
Common Mistakes To Avoid
- Pupils often over-generalise the word 'base' and do not recognise that the base is not always horizontal or the 'bottom' part of the shape.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The area of a triangle is half the area of a parallelogram with same base and perpendicular height. The area of a triangle can be calculated using the formula area = base × perpendicular height ÷ 2.
2. Use this key word in a maths sentence and explain it clearly. 'Parallelogram'
A parallelogram is a quadrilateral with two pairs of parallel and equal sides. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils often over-generalise the word 'base' and do not recognise that the base is not always horizontal or the 'bottom' part of the shape. Correction: Take time to identify that the base is related to the perpendicular height and show that one triangle can have a different base dependent on where the measurement is taken from. Pupils should consider efficiency when selecting a base.
More Lessons In This Unit
- Describe the relationship between scale factors and perimeters of two shapes Study Guide
- Draw and complete simple shapes by plotting positions on the full coordinate grid Study Guide
- Draw and translate simple shapes on the full coordinate grid Study Guide
- Explain how to calculate the area of a parallelogram Study Guide
- Reflect simple shapes in the axes on a full coordinate grid Study Guide
- Solve problems involving area and perimeter Study Guide
- Solve problems involving missing coordinates Study Guide
- Use the area of a parallelogram formula to calculate unknown measurements Study Guide
- Use the area of a triangle to calculate unknown measurements Study Guide
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