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  • Early Years Foundation Stage

Name That Triangle!

Age 7 to 11
Challenge Level Yellow star
Primary curriculum
  • Problem
  • Getting Started
  • Student Solutions
  • Teachers' Resources

What different types of triangle can you think of?

  

See how many you can name, then click on the buttons below to find out what some other children have said.

Edd said:


"There are four types of triangle: equilateral, isosceles, scalene and right-angled."


Fleur said:


"There are only three types of triangle. These are equilateral, isosceles and scalene. Right-angled triangles don't count because all right-angled triangles are also isosceles or scalene triangles."


Harmony said:


"You can name a triangle using either the sides or the angles of the triangle. Using the sides, you can have equilateral, isosceles and scalene triangles. Using the angles, you get right-angled, acute or obtuse triangles."


Which of these children do you agree with? Why?

We normally name triangles by thinking about the lengths of the sides, but in this activity we will also be naming triangles using their angles. How could we do this? What do you think an 'acute triangle' or an 'obtuse triangle' might look like?

Have a look at the grid below. 

  

This grid is to help us think about different properties of triangles.  For example, a triangle drawn in the box at the top on the left, should be able to be described as both acute (when thinking about its angles) and equilateral (when thinking about its sides).

Look at each space on the grid and try to sketch some different triangles to go in the box.
Can you sketch a triangle for every box in the grid? Why/why not?

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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