Congruent triangles (SSS)
I can appreciate and use the criteria by which triangles are congruent (SSS).
Congruent triangles (SSS)
I can appreciate and use the criteria by which triangles are congruent (SSS).
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- By knowing the three side lengths of the triangle and its image, you can prove congruence.
- The corresponding 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.
Common misconception
Pupils may believe that as the sides fix the angles, that this implies it is true conversely.
Use any regular polygon to highlight that the angles will always be the same, but the edge lengths are not always the same length. Regular polygons are always similar but not necessarily congruent.
To help you plan your year 9 maths lesson on: Congruent triangles (SSS), download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 9 maths lesson on: 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 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



AB -
GF
CD -
EH
BC -
EF
∠DCB -
∠FEH
∠ADC -
∠EHG
∠DAB -
∠HGF
Square -
Rectangle
Parallelogram -
Rhombus
Isosceles trapezium -
Parallelogram
Kite -
Trapezium
Exit quiz
6 Questions

AB -
QR
BC -
PR
AC -
QP


ST = SV -
as ST and SV are both edges of the same square.
TU = VU -
as TU and VU are both edges of the same square.
SU -
is a common edge to both triangles.






a -
PQ
b -
QR
c -
PR