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## 'Three Fingers and a Loop of String' printed from http://nrich.maths.org/

This is a very simple exploration of types of triangles, but can
provide stimulation some interesting discussion and development of
vocabulary. Asking the children to draw, compare and sort the
triangles contributes to the perception and understanding of the
basic properties of triangles.

Here is an example of a series of activities that could prompt
the children to think about triangles and discover some of their
characteristics.

Ask each child to make a triangle with his/her loop and ask
several children to talk about their triangle and explain how they
know it's a triangle. If responses are very vague - don't try to
'teach' a better answer yet, just move on.

Invite the children to move their fingers to create another
triangle and hold it in place. Ask each child to try to find
someone else who has made a triangle that looks the same.

Choose some children to explain why the triangles are the
same.

Now ask the children to find someone who has a 'different'
triangle, and choose some children to explain the differences.

Ask the children to form work pairs and have them make at least
five different triangles, drawing each triangle on separate pieces
of paper. Invite the pairs to now sort their triangle drawings into
two (or more groups). Bring pairs together and have them explain
their groupings to each other. Ask the foursomes to now put all
their triangles together and agree on a sorting system, which can
be displayed and labelled to share with the rest of the class.
Finally, return to step one and ask each child to make an triangle,
talk about it and explain why it's a triangle. Have they
improved?