Congruent Triangles | I Do, We Do, You Do | Year 9 Maths | Print Free

Teach pupils to prove triangle congruence with this 97-slide Year 9 maths PowerPoint. Explore SSS, SAS, ASA and RHS, match corresponding sides and angles, and explain why AAA and general SSA do not establish congruence.

Designed for print-free teaching: project the labelled diagrams while pupils answer on mini whiteboards or in exercise books. No printed worksheets, measuring or pupil construction tasks are required.

ANIMATIONS THAT EXPLAIN WHY
Four animated demonstrations show how SSS, SAS, ASA and RHS fix a triangle. Pupils see side-length arcs intersect, an included angle fix an opening, angle rays meet and a hypotenuse constrain a right-angled triangle. Reflected alternatives illustrate why different orientations can still be congruent.

Three further animations show exact overlap, an AAA counterexample and two different triangles sharing the same SSA facts. The embedded animations repeat automatically in PowerPoint Slide Show.

I DO, WE DO, YOU DO
A six-question I Do / We Do overview provides three matched pairs, small diagrams and space for teacher working. Enlarged questions and worked answers model SSS, SAS and ASA proofs. Further examples explore RHS, finding a missing angle before using ASA, and insufficient evidence.

32 QUESTIONS ACROSS TWO PRACTICE PAGES
Shared galleries of labelled triangles support questions about congruence conditions, corresponding parts, included angles and hypotenuses. Pupils justify conclusions, challenge incorrect claims and consider how changing or removing a fact affects a proof.

ONE-PAGE DIFFERENTIATED TASK
One rectangle diagram containing several triangles supports nine Developing, six Secure and four Greater Depth questions, plus a Super Challenge.

Developing begins with lengths, right angles and hypotenuses. Secure builds complete proofs using different conditions. Greater Depth asks pupils to reason with hidden facts, test a two-side claim and use congruence to establish equal angles.

The illustrated Super Challenge tests whether equal angles and an equal non-corresponding side guarantee congruence. Full answers are included.

CHECK UNDERSTANDING THROUGHOUT
• Six retrieval questions and six prerequisite questions, with grouped answers.
• Twenty individual mini-whiteboard AFL questions, each immediately followed by its answer.
• Diagrams supporting all AFL questions and three exit checks.
• Complete practice, differentiated-task and challenge answers.
• Editable lesson text and static diagrams, with embedded animated demonstrations.