Tracking triangles in #MondayMaths

Monday Maths: Vicki Robinson, Communications Officer

Tracking triangles in #MondayMaths

Posted: 23/01/17

Here’s a tricky triangular treat for your dose of #MondayMaths – we’re asking you to track the path of a triangle and imagine sliding it around itself. You’ll need to apply a range of mathematical skills to crack this one.

Whether it’s a classroom teaser or a homework puzzle, this is great to try out with Year 9 students when looking at 2D Geometry (angles on lines and in triangles), this term.

Problem solving hats on

For students giving this a go, they can approach it in lots of different ways – but first of all, they need to identify what it means for triangles to be congruent with each other.

Once they’ve got that cracked, they could start by sketching a simple triangle on squared paper, like an isosceles right angle triangle. Can they work out the answer using this and will it be the same rule for all types of triangles?

Alternatively, they could cut out a selection of congruent triangles and use them to trace the path as described.

Discussing in pairs

Encourage students to ask each other questions to assist in their workings out:

  • Can we visualise the path made by the triangle – what’s the shape of the path? (Students will need to work out where the vertices of the path are as well as identify the length of the path)
  • How does this path relate to the original triangle?
  • And most importantly, can we explain our answers to these questions?

Flip it around

To make the most out of this puzzle and reuse it for future lessons, how about adapting the question using different shapes.

Does the same rule still apply?

This week’s answer will be on our Twitter page on Thursday. Good luck!

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

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