Reflect polygons that are dissected by the line of symmetry
Lesson details
Learning outcome
I can reflect polygons that are dissected (cut in half) by the line of symmetry, and explore the new shapes that are created when a polygon is reflected.
Key learning points
- When you reflect a shape, each vertex will be the same distance from the line of symmetry.
- When you reflect a polygon that has a side that is touching the mirror line, you can sometimes create a new shape.
Keywords
Line of symmetry - If you were to fold a shape on its line of symmetry, both halves would match exactly.
Mirror line - Mirror line is another term to describe the line of symmetry.
Reflect - When you reflect a shape, you flip it over a mirror line or line of symmetry without turning it or changing the size.
Reflection - The reflection of a shape is the mirror image of a shape.
Common misconception
Children may miscount the number of squares from the mirror line when plotting each vertex to reflect the shape.
Encourage children to work systematically by only marking one vertex at a time to reduce the chance of errors. Also encourage use of mirrors to check.
Teacher tip
Although this lesson has been designed to teach other strategies for reflecting in a line of symmetry, children may benefit from being able to use mirrors to support their understanding of reflective symmetry.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.The reflection of a shape is sometimes called a __________.
Q2.Which image shows a reflection?
Q3.True or false. This image shows a reflection.
Q4.Which image shows a reflection?
Q5.Sam is using vertices to reflect this shape. Which vertex is in the wrong position on the grid?
Q6.Complete the sentence. This image does not show a reflection because __________
Assessment exit quiz
6 Questions
Q1.This shape has been reflected. Each vertex is __________ from the line of symmetry.
Q2.Which of these images shows a correct reflection?
Q3.Which of these images shows a correct reflection?
Q4.Which of these images is not a correct reflection?
Q5.Here are are three different triangles that have been reflected in the line of symmetry. Name the new shapes that have been made.
triangle
square
kite
Q6.True or false. When you reflect a rectangle that has a side that touches the mirror line, it will create a larger rectangle.
To help you plan your 4 maths lesson on: Reflect polygons that are dissected by the line of symmetry, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 4 maths lesson on: Reflect polygons that are dissected by the line of symmetry, 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 Properties of 2D and 3D shapes and symmetry unit, dive into the full primary maths curriculum, or learn more about lesson planning.