Important discoveries about triangles can be made through creating these 3-sided shapes.   Children will discover how rigid triangles are, and that three fixed lengths can only be arranged in one way, unlike other polygons such as quadrilaterals where the angles can be changed.



Age 5 to 7 

Charlie and Addy are making triangles with a construction set. They have a pile of strips of different lengths.

There are:

  • yellow strips with 3 holes

  • black strips with 4 holes,

  • red strips with 5 holes and

  • green strips with 6 holes.

There are plenty of strips of each color.

Charlie makes a triangle with a green strip, a yellow strip and a red strip.

Addy makes a triangle with two green strips and one red strip and another triangle with three black strips.

two triangles.

How many different triangles can you make with these lengths?

Can you find three strips which cannot be made into a triangle when you use them together?

Let’s Investigate Triangles pdf



Age 5 to 7 

Explore the triangles that can be made with seven sticks of the same length.