Myths about teaching can hold you back
- Year 10•
- Higher
Checking and securing understanding of congruent triangles (SSS)
I can understand and use the criteria by which triangles are congruent (SSS).
- Year 10•
- Higher
Checking and securing understanding of congruent triangles (SSS)
I can understand and use the criteria by which triangles are congruent (SSS).
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Lesson details
Key learning points
- By knowing the three side lengths of the triangle and its image, you can prove congruence.
- If congruent, the same multiplicative relationship will exist for each pair of side lengths.
- The angle pairs will be the same.
Keywords
Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.
Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.
Common misconception
Pupils may believe that knowing the three angles is sufficient to prove two triangles are congruent.
Use an equilateral triangle to show that, although two equilateral triangles have the same angles, they are not guaranteed to be congruent. In fact they are similar.
To help you plan your year 10 maths lesson on: Checking and securing understanding of congruent triangles (SSS), download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 10 maths lesson on: Checking and securing understanding of congruent triangles (SSS), 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 4 maths lessons from the Similarity unit, dive into the full secondary 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.__________ is the multiplier between similar shapes that describes how large one shape is compared to the other.
Q2.This sector is enlarged by scale factor $$\frac{1}{3}$$. The angle in the image is °.
Q3.Each square on this coordinate grid is 1 unit long. This object is enlarged by a scale factor of 3 to make its image. The perimeter of the image is cm.
Q4.A pentagon has a perimeter of 60 cm. The pentagon is enlarged by scale factor 5. The perimeter of the image is cm.
Q5.The object is enlarged by a scale factor of $$\frac{1}{4}$$ to make the image. What is the perimeter of the image?
Q6.A shape is enlarged by a scale factor of $$\frac{2}{5}$$ to make its image. The perimeter of the image is 28 cm. The perimeter of the object is cm.
Assessment exit quiz
6 Questions
Q1.Alex says, "If one shape can fit exactly on top of another using __________, __________ or translation, then the shapes are congruent." Select the words that correctly complete Alex's statement.
Q2.Which of these pairs of shapes look like they are congruent to each other?
Q3.Some Oak pupils are discussing congruence. Which pupils are correct?
Q4.The diagram shows a pair of congruent triangles. The length of the side marked $$x$$ is m.
Q5.The diagram shows a pair of congruent triangles. Which of these Oak pupils are making a correct statement?
Q6.Select the statements needed to prove the following: "The diagonal of a rhombus bisects the shape into two congruent triangles."
