Investigate different ways of decomposing a polygon
Lesson details
Learning outcome
I can decompose a polygon in different ways and identify properties of polygons.
Key learning points
- The same whole can be split into different parts.
- Lines are perpendicular when they are at right angles to each other.
- Lines are parallel because they are always the same distance apart.
Keywords
Polygon - A polygon is a 2D shape made up of three or more straight lines.
Quadrilateral - A quadrilateral is a polygon that has four straight sides and four vertices.
Parallel - Parallel lines are straight lines that are always the same distance apart. They never get closer together or further apart.
Decompose - To decompose means to break something into parts that are the same as the original when you put them back together.
Common misconception
Pupils are not able to identify right angles and therefore struggle to identify pairs of perpendicular sides.
Provide children with a right angle checker. Take time to model its use, focusing on aligning one edge of the checker with a side of the angle they want to check.
Teacher tip
Decomposing shapes is a really useful tool for later thinking about area, fractions and spatial reasoning. Ensure pupils have adequate time in this lesson to decompose polygons and discuss similarities and differences.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Match the polygons to the correct name.
pentagon
octagon
quadrilateral
triangle
Q2.Match the parts of the sentence correctly.
is a triangle.
is a pentagon.
is a hexagon.
is an octagon.
Q3.Which of these are properties of a rectangle?
Q4.Look at this pentagon.
How many right angles does it have? right angles
Q5.Look at this hexagon.
How many right angles does it have? right angles
Q6.This rectangle has been cut in half using a diagonal line. What shape will both halves be?
Assessment exit quiz
6 Questions
Q1.How many pairs of parallel sides does this quadrilateral have?
Q2.The pentagon has been decomposed into three polygons. Match the name of the polygon to the correct letter.
triangle
triangle
quadrilatral
Q3.This hexagon has been decomposed into two shapes. Select the names of the decomposed shapes.
Q4.Two lines that meet at a right angle are called __________ lines.
Q5.Look at the image. Which statements are true?
Q6.This octagon has been decomposed into 3 polygons. Match each polygon to the correct description.
has one pair of parallel sides.
has only two right angles.
has more than one pair of perpendicular sides.
To help you plan your 3 maths lesson on: Investigate different ways of decomposing a polygon, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 3 maths lesson on: Investigate different ways of decomposing a polygon, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 2 maths lessons from the Parallel and perpendicular sides in polygons unit, dive into the full primary maths curriculum, or learn more about lesson planning.