Reflect polygons that are dissected by the line of symmetry
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.
- Year 4
Reflect polygons that are dissected by the line of symmetry
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.
Lesson details
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.
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.
Q6.True or false. When you reflect a rectangle that has a side that touches the mirror line, it will create a larger rectangle.
