A triangle is a polygon. It is a closed 3-sided shape made up of straight lines. The ‘tri-’ part of the word triangle means three. A triangle has 3 sides and 3 angles. Interior angles are the angles ...

Understanding different types of angles and that angles in a triangle sum to 180° can be helpful when classifying a triangle. Recognising line symmetry and rotational symmetry will also help. Look for ...

Big Idea – We can describe, measure, and compare spatial relationships. to build on students' knowledge of triangle and develop students' reasoning with properties of different classes of triangles to ...