Year 3 - Maths
Make shapes by joining two polygons in different ways
Parallel and perpendicular sides in polygons
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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 investigate ways to compose and decompose polygons. They will investigate quadrilaterals with and without parallel and perpendicular sides.
Lesson Summary
You will learn to make compound shapes by joining two polygons in different ways.
Key Notes
- The same parts can create a different whole.
- Lines are parallel because they are always the same distance apart.
- A quadrilateral with two pairs of parallel sides is called a parallelogram.
Vocabulary To Learn
- Polygon: A 2D shape made up of three or more straight lines.
- Quadrilateral: Polygons with four straight sides and four vertices.
Common Mistakes To Avoid
- Pupils do not recognise the new shape and only identify the smaller shapes it is composed of.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The same parts can create a different whole. Lines are parallel because they are always the same distance apart.
2. Use this key word in a maths sentence and explain it clearly. 'Polygon'
A 2D shape made up of three or more straight lines. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils do not recognise the new shape and only identify the smaller shapes it is composed of. Correction: Using plastic shapes to compose a new shape and drawing around the shape can support pupils to see the properties of the new shape. Drawing around removes the joined sides inside the new polygon.
More Lessons In This Unit
- Construct quadrilaterals with and without parallel and perpendicular sides Study Guide
- Draw polygons on isometric paper Study Guide
- Draw shapes with given properties Study Guide
- Draw shapes with given properties on a range of geometric grids Study Guide
- Identifying parallel lines Study Guide
- Investigate different ways of decomposing a polygon Study Guide
- Make and draw quadrilaterals on circular geoboards Study Guide
- Make and draw shapes with and without parallel and perpendicular sides Study Guide
- Make and draw triangles on circular geoboards Study Guide
Browse all guides in the Year 3 Maths guide library.