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

Make triangle construction visible with this 115-slide Year 9 maths PowerPoint. Nine animated demonstrations show the steps, while diagram-based questions check understanding and practical tasks get pupils constructing triangles themselves.

Teach ASA, SAS, SSS and RHS constructions, including obtuse angles, isosceles and equilateral triangles, impossible constructions and two possible triangles from the same information.

PRINT-FREE TEACHING, WITH PRACTICAL CONSTRUCTION
Project the lesson and use mini whiteboards for short answers and construction decisions. Dedicated practice and differentiated construction pages ask pupils to draw accurately in exercise books using a ruler, protractor and compasses. No printed worksheets are needed.

NINE ANIMATED DEMONSTRATIONS
Show angle rays meeting, compass arcs locating a vertex and the correct order of construction. Further animations cover obtuse ASA and SAS examples, equal-radius arcs, an equilateral triangle and the two-intersection challenge. Animations repeat in PowerPoint Slide Show, with static diagrams and explanations alongside them.

I DO, WE DO, YOU DO
A six-question I Do / We Do overview provides three matched pairs, small diagrams and teacher working space. Enlarged questions and worked solutions develop choices about tools, compass centres, radii and angle directions. Further examples cover RHS and equilateral constructions.

PRACTICE THAT BUILDS UNDERSTANDING
• 32 diagram-based questions across two practice pages: choose construction steps, diagnose errors and explain how changing information affects a triangle.
• 12 actual construction questions on one page, with worked diagrams and step-by-step answers.
• A shared-diagram differentiated task with nine Developing, eight Secure and four Greater Depth questions, plus a Super Challenge.
• An additional one-page construction task with four Developing, four Secure and three Greater Depth questions, plus a practical version of the Super Challenge.

Greater Depth includes calculating a missing angle before construction, showing why arcs cannot meet and constructing non-congruent triangles with two fixed sides. The Super Challenge asks pupils to construct both possible triangles and measure the two possible lengths.

CHECK UNDERSTANDING THROUGHOUT
Six retrieval questions and six prerequisite questions have grouped answers. Twenty individual mini-whiteboard AFL questions each have an immediate answer slide. Three exit checks assess understanding at the end. Worked answers support both the reasoning tasks and practical constructions.

YOUR DOWNLOAD
One PowerPoint containing the complete lesson and answers, with editable text and static diagrams plus embedded animations. Created by Beyond Printables for Year 9, Unit 23, U187: Constructing Triangles.