Try continuing these patterns made from triangles. Can you create your own repeating pattern?

Watch this "Notes on a Triangle" film. Can you recreate parts of the film using cut-out triangles?

This practical problem challenges you to create shapes and patterns with two different types of triangle. You could even try overlapping them.

What do these two triangles have in common? How are they related?

In how many ways can you fit two of these yellow triangles together? Can you predict the number of ways two blue triangles can be fitted together?

This problem invites you to build 3D shapes using two different triangles. Can you make the shapes from the pictures?

You have been given nine weights, one of which is slightly heavier than the rest. Can you work out which weight is heavier in just two weighings of the balance?

Here is a solitaire type environment for you to experiment with. Which targets can you reach?

Using the interactivity, can you make a regular hexagon from yellow triangles the same size as a regular hexagon made from green triangles ?

If the yellow equilateral triangle is taken as the unit for area, what size is the hole ?

Which of these triangular jigsaws are impossible to finish?

Can you work out where the blue-and-red brick roads end?

A game in which players take it in turns to choose a number. Can you block your opponent?

If you think that mathematical proof is really clearcut and universal then you should read this article.

Solve the equations to identify the clue numbers in this Sudoku problem.