Solve problems involving the perimeter and side lengths of polygons
Lesson details
Learning outcome
I can use knowledge of side lengths and perimeter to solve problems.
Key learning points
- Perimeter is the sum of the side lengths of a 2D shape.
- Mental and written methods can be used to calculate the perimeter of a 2D shape.
- Combinations of addition, subtraction, multiplication and division can be used to solve problems involving perimeter.
Keywords
Perimeter - The distance around a two-dimensional shape.
Regular - A regular polygon has all sides equal and all angles equal.
Common misconception
Pupils may think that if they know the perimeter of a shape, and a new shape has been made from duplicates of it, they can simply multiply the perimeter by how many shapes make up the new one.
The lesson highlights this misconception and tackles it but it is worth being aware of it as pupils work. Point out to them that some of the sides from the original shape are now inside the new shapes so do not count as part of its perimeter.
Teacher tip
This lesson has been presented pictorially but if you have access to physical regular shapes, you could redesign the lesson based around these to provide pupils with a memorable hands-on problem solving experience.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Continue the sequence:
3, 6, 9, 12,
Q2.Which of these numbers would you say if you were counting in fours from zero?
Q3.Match the number of sides to the shape name.
Q4.What is the side length of a square with a perimeter of 20 cm?
Q5.What is the side length of a regular triangle with a perimeter of 30 cm? cm
Q6.What is the side length of a regular five-sided polygon with a perimeter of 25 cm? cm.
Assessment exit quiz
6 Questions
Q1.A regular triangle and a square have the same perimeter, which is a whole number. What could the perimeters be?
Q2.A regular triangle and a square each have a perimeter of 12 cm. What is the side length of each shape?
Q3.Shape A is a square with a perimeter of 16 cm. A new shape has been composed from copies of shape A. What is its perimeter? cm.
Q4.Shape A is a square with a perimeter of 16 cm. A new shape has been composed from copies of shape A. What is its perimeter? cm.
Q5.Shape A is a square with a perimeter of 12 cm. A new shape has been composed from copies of shape A. What is its perimeter? cm.
Q6.Shape A is a regular hexagon with a perimeter of 30 cm. A new shape has been composed from copies of shape A. What is its perimeter? cm.
To help you plan your 4 maths lesson on: Solve problems involving the perimeter and side lengths of polygons, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 4 maths lesson on: Solve problems involving the perimeter and side lengths of polygons, 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 Perimeter unit, dive into the full primary maths curriculum, or learn more about lesson planning.