Myths about teaching can hold you back
- Year 8
Deriving the sum of interior angles in multiple ways
I can use reasoning to derive the sum of interior angles in multiple ways.
- Year 8
Deriving the sum of interior angles in multiple ways
I can use reasoning to derive the sum of interior angles in multiple ways.
Lesson details
Key learning points
- Not all vertices of component shapes contribute to the sum of the interior angles of a composite shape.
- A numerical sequence can be used to derive the sum of interior angles.
- A formula can be derived to find the sum of interior angles.
Keywords
Polygon - A polygon is a flat (2D), closed figure made up of straight line segments.
Interior angle - An interior angle is an angle formed inside a polygon by two of its edges.
Sum - The sum is the total when numbers are added together.
Common misconception
Interior angles always sum to 180 times the number of component triangles it is split into.
If line segments drawn make new vertices in the polygon, its angles won't contribute to the sum of interior angles in the initial polygon.
To help you plan your year 8 maths lesson on: Deriving the sum of interior angles in multiple ways, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 8 maths lesson on: Deriving the sum of interior angles in multiple ways, 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 3 maths lessons from the Geometrical properties: polygons unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.A is a flat (2D), closed figure made up of straight line segments.
Q2.What is the size of ∠BCD?
