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# Nine-pin Triangles

Links to the University of Cambridge website
Links to the NRICH website Home page

Nurturing young mathematicians: teacher webinars

30 April (Primary), 1 May (Secondary)

30 April (Primary), 1 May (Secondary)

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Age 7 to 11

Challenge Level

How many different triangles can you make on a circular pegboard that has nine pegs?

You may like to use the interactivity to try out your ideas. Click on two of the dots to create a line between them.

If you prefer to work on paper, you might find this sheet of nine-peg boards useful.

Once you've had a go at this, why not investigate the number of different triangles you can create on circular pegboards with more or fewer pegs?

You might also like to have a look at this task for some extension questions!

*Many thanks to Geoff Faux who introduced us to the merits of the nine-pin circular geoboard.*

For further ideas about using geoboards in the classroom, please see Geoff's publications available through the Association of Teachers of Mathematics (search for 'geoboards').

You may like to use the interactivity to try out your ideas. Click on two of the dots to create a line between them.

If you prefer to work on paper, you might find this sheet of nine-peg boards useful.

Once you've had a go at this, why not investigate the number of different triangles you can create on circular pegboards with more or fewer pegs?

You might also like to have a look at this task for some extension questions!

For further ideas about using geoboards in the classroom, please see Geoff's publications available through the Association of Teachers of Mathematics (search for 'geoboards').