Applying the criteria for congruence
I can identify congruent triangles and prove why they are congruent.
Applying the criteria for congruence
I can identify congruent triangles and prove why they are congruent.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- If two triangles are congruent, then one of the proven criteria must apply.
- By stating the criteria (that you have already proven), you can prove congruence.
- It is important to be clear why you know that two triangles are congruent.
Keywords
Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.
Common misconception
Pupils may think they need to know the actual size or length to be able to prove congruence.
Remind pupils that if they can show that the corresponding angles or sides are the same length, then that is all that is needed. For example, if the corresponding edges are both edges of the same regular polygon, then they will be the same.
To help you plan your year 9 maths lesson on: Applying the criteria for congruence, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 9 maths lesson on: Applying the criteria for congruence, 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: similarity and Pythagoras' theorem unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions









Exit quiz
6 Questions





a -
CD
b -
DE
c -
angle CDF
d -
angle CDE