#MondayMaths and a congruent conundrum

Monday Maths: Vicki Robinson, Communications Officer

#MondayMaths and a congruent conundrum

Posted: 2/01/17

Welcome back to a new term! We hope you all enjoyed your festive break and celebrations.

Our first #MondayMaths puzzle for 2017 is full of tricky triangles – we’re describing two triangles and asking you to show how you can construct one from the other. We also want you to outline the steps and tools needed to ensure your construction is accurate.

Where does this fit in?

This puzzle would work well as a classroom task for Year 9 students this term where they look at congruent shapes and constructions as part of 2D geometry. This unit builds on their learning of angles and triangles in Year 8.

It would also work well as a depth task in Year 8 as the problem requires some knowledge of angles in parallel lines, a topic that is covered in Unit 5.

Get cracking

Here are some short and sweet ideas to get your class started:

  • Ask your class to identify properties of triangle PQR – does it have any identical angles or parallel lines?
  • To help visualise the scale factor, encourage students to sketch out the diagram themselves and see what they notice
  • Your class can also tackle this practically by cutting out identical triangles to demonstrate and tease out the congruence


We recommend Don Steward’s blog for more tips on teaching this topic!

Our puzzles are solved on our Twitter page every Thursday. Get involved and share your feedback with us.

Looking for more ideas for your lessons? Take a look at our free classroom resources.

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