Students learn how to identify and describe reflective symmetry in 2D shapes using mirror lines.
Later, learning progresses from finding reflective symmetry in 2D shapes to performing reflections in diagonal mirror lines.
Reflective symmetry is the first lesson in the topic on transformations at key stage 3. At the start of the lesson I want students to remember the basic properties of 2D shapes before we begin the lesson.
I ask students to work in pairs and on mini-whiteboards so I can assess their understanding. This helps me to know the level to pitch the next part of the lesson.
After working through the examples, shown in the video above, I give students a copy of this activity to save them time from having to draw the shapes. While more able students can identify the lines of symmetry with no equipment I handout reflective strips for those who need it.
At first, a few students identify only one line of symmetry for the blue shape. This is easily addressed when I ask them to rotate a reflective strip around the centre of the shape.
Rather than having to feedback the solutions I encourage students to use the reflective strip to check their solutions.
This question links back to the starter and is a nice way of showing the progress students have made. Again, I provide a handout for the students to work out. This activity takes about 5 – 8 for most students.
There are many solutions to questions a) and c) so I ask students to find as many as possible.
My name is Jonathan Robinson and I am passionate about teaching mathematics. I am currently Head of Maths in the South East of England and have been teaching for over 15 years. I am proud to have helped teachers all over the world to continue to engage and inspire their students with my lessons.
Key Stage 3 lesson on identifying lines of reflective symmetry in 2D shapes.
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