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Supporting Australian Mathematics Project: Middle years.

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Year 5

Measurement and Geometry

Angles – measurement, construction, estimation

When two lines meet at a point, they make an angle. The two lines are called the arms of the angle and the point is called the vertex.

Two arms of an angle meet at the vertex, labelled O
Detailed description

Two angles are created. One angle falls inside the arms, and the other angle falls outside them.

Two angle diagrams, showing acute angle and obtuse angle.
Detailed description

To measure the angle we see how much one of the lines must be turned through the shaded area to get to the other line.

An understanding of angles forms the basis of much of the geometry you will meet in upper primary and in secondary school. Geometry, including angles, has been used throughout history. The Egyptians must have had a very good knowledge of angles to construct the pyramids so perfectly.