Shape, Space and Measure is definitely my favourite area of Maths when teaching, so I look forward to teaching construction of triangles. Some of you may have heard of the National Geographic Trading Game: students simulate the trading of goods between countries, before reflecting on the challenges of trade between countries. But where does this fit into constructing triangles?

Triangles are sturdy; while a rectangle can collapse into a parallelogram from pressure to one of its points, triangles have a natural strength which supports structures against lateral pressures. A triangle will not change shape unless its sides are bent or extended or broken or if its joints break; in essence, each of the three sides supports the other two. A rectangle, in contrast, is more dependent on the strength of its joints in a structural sense.

It follows that it is important to construct a triangle with complete accuracy, but I found that pupils get bored and sometimes sloppy when constructing triangles from a textbook. So I adapted the trading game to ‘Trading Triangles’….

The task is for each group to work as a business, investing in initial overheads and building materials to construct and sell as many accurate triangles as possible while also responding to changing market conditions.

You will need:

·         Pencils

·         Compasses

·         Protractors

·         Card

·         Rulers

·         Scissors

·         Fake Money – I made my own (quite time consuming, so instead consider investing in some ‘play money’ online)

‘Trading Triangles’  requires pupils to work in groups (or businesses) with each pupil assigned a different role – ‘Project Manager’, ‘Sales Rep’ or ‘Treasurer’.

Project Manager – the role of the project manager is to make decisions on how best to approach the task including how best to make a profit and delegating jobs to the rest of the company. The project manager will have to communicate with the treasurer to find out what money can be spent on machinery and equipment. They will also have to liaise with the sales rep on how best to improve constructions.

Sales Rep – the role of the sales rep is to take constructed triangles to the buyer and sell their product. The sales rep will also be responsible for communication between the buyer and their team regarding feedback

Treasurer – the role of the treasurer is to look after the company’s budget. The treasurer must ensure that the company is not overspending on machinery and materials.

At the beginning of the lesson we discussed why triangles where important and why it is important for them to be constructed accurately showing examples of triangles in buildings.

Once pupils have bought the equipment (machinery) they need to construct the triangles accurately so that they can then take them to the banker (who has templates for marking – I made these with a 2mm allowance on tracing paper) to sell. Throughout the lesson the market conditions will change reflecting the current economic climate and natural disasters (all communicated to the pupils via the flipchart) so that different triangles are in higher demand, earning greater profits.

I chose the groups and assigned roles to pupils depending on their strengths or weaknesses, but it could be interesting to let students choose for themselves, based on their perceived strengths. At the end of the lesson, I discussed what strategies pupils put in to place, for example: did they use mass production? How did they employ each member of their group? Did they overspend/underspend on materials?

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Please feel free to give this lesson a try and make adjustments to suit your lesson and pupils. Let me know how it goes, I have only tried this lesson on a couple of occasions and next time I am considering an extra role – ‘the engineer’ as well as a variety of different triangles.

With the many of triangles produced as part of the game and a few photos, you can also use the work to produce a nice and easy display in your classroom.

A cancer-fighting, maths loving teacher in London

### 3 responses »

1. Dave Gale says:

Now that’s a really good idea!
I find construction lessons tedious but this really captures my motivation (I love games).

Thanks for sharing.

Dave

2. misterheller says:

That looks great.

I cannot download the ‘Banker Details’ Can you send me a link that works?

Thanks

@Mr_Heller_Kes