Acute Triangle Area


This task gets students to discover the different classifications of triangles for themselves by grouping them according to various properties. What starts out as a very simple question then leads into a rich discussion that is sure to get your students thinking deeply about the mathematics involved.

Learning Goal:

  • To be able to classify triangles according to their properties

Success Criteria:

  • Classify triangles based on a property of your choice
  • Classify triangles according to side lengths
  • Classify triangles according to interior angles.
  • Construct triangles according to their classification.
How many Triangles
How many Triangles can you see in each of the following shapes?

How about a Size 10? How do you know?

Triangular paddocks
To save money on fencing, a farmer decides to make triangular paddocks lined up against each other like so:

If they use 2 fence railings for each side of the paddock, how many fence railings would they need for different size paddocks?


3D objects
Get students to make different prisms and 3D objects out of Unifix cubes. Use the Isometric paper to draw these 3D shapes on paper.