Triangles

problem
Isosceles seven

Age

14 to 16

Challenge level

Is it possible to find the angles in this rather special isosceles triangle?
problem
Triangle in a square

Age

7 to 11

Challenge level

Do you agree with Badger's statements? Is Badger's reasoning watertight? Why or why not?
problem
Possible pairs

Age

7 to 11

Challenge level

In this game, you turn over two cards and try to draw a triangle which has both properties.
problem
Triangle or no triangle?

Age

5 to 7

Challenge level

Here is a selection of different shapes. Can you work out which ones are triangles, and why?
problem
Name that triangle!

Age

7 to 11

Challenge level

Can you sketch triangles that fit in the cells in this grid? Which ones are impossible? How do you know?
problem
Triangle transformation

Age

7 to 14

Challenge level

Start with a triangle. Can you cut it up to make a rectangle?
game

Board block for two

Age

5 to 7

Challenge level

Board Block game for two. Can you stop your partner from being able to make a shape on the board?
article
Peg and pin boards

This article for teachers suggests activities based on pegboards, from pattern generation to finding all possible triangles, for example.
problem
Three triangles

Age

7 to 11

Challenge level

What do you notice when you put three triangles together?
problem
Constructing triangles

Age

11 to 14

Challenge level

Generate three random numbers to determine the side lengths of a triangle. What triangles can you draw?