- Year 3
Investigate the shapes made when rectangles are cut on the diagonal
I can describe the shapes made when rectangles are cut on the diagonal.
- Year 3
Investigate the shapes made when rectangles are cut on the diagonal
I can describe the shapes made when rectangles are cut on the diagonal.
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Lesson details
Key learning points
- An angle can be exactly a right angle.
- An angle can be less than or greater than a right angle.
- When you cut a square using two diagonal lines, you get four identical triangles.
- When you cut a rectangle that is not a square using two diagonal lines, you get two pairs of identical triangles.
Keywords
Diagonal - A straight line connecting one vertex to another, but is not the side or edge.
Common misconception
Pupils may find it hard to recognise when an angle is greater than a right angle.
You can model this by trying to move the obtuse angle (though pupils don't need to know the term yet) within a right angle checker. They should be able to see that it is too large to fit.
To help you plan your year 3 maths lesson on: Investigate the shapes made when rectangles are cut on the diagonal, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 3 maths lesson on: Investigate the shapes made when rectangles are cut on the diagonal, 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 Right angles unit, dive into the full primary maths curriculum, or learn more about lesson planning.
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Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of these shapes are rectangles?
Q2.Which of these shapes are squares?
Q3.Why is this shape not a rectangle?
Q4.Match the description to the type of shape.
A four-sided polygon with 4 right angles.
Any four-sided polygon.
A four-sided polygon with 4 right angles and 4 equal sides.
Q5.5. Match each line to the correct name.
diagonal
vertical
horizontal
Q6.Look at this pattern. How many rectangles are there altogether?
Assessment exit quiz
6 Questions
Q1.Aisha cuts this rectangle in half using a vertical line.
What shape will both halves be?
Q2.Aisha cuts this rectangle in half using a diagonal line.
What shapes will both halves be?
Q3.Aisha cuts this square into two triangles using one diagonal line.
Which of these statements is true?
Q4.Laura uses two diagonal lines, cutting from each vertex at the top of the square to each at the bottom.
How many triangles would the rectangle be cut up into?
Q5.Aisha cuts a rectangle into four triangles. This is one of the triangles. How many angles inside the shape are smaller than a right angle?
