The key idea of shape at Level 5 is that geometric properties of shapes can be used to calculate lengths and angles.
At level 5 students are able to use rules relating to geometric properties to calculate unknown angles, and lengths. The properties used include internal and external angles of polygons, and angles on intersecting and parallel lines. This links to the key idea of measurement at level 5 which includes calculating areas and volumes based on edge lengths.
This key idea develops from the key idea of shape at level 4 where students are developing an understanding of 2-dimensional representations of 3-dimensional shapes.
This key idea is extended in the key idea of shape at level 6 where a wider variety of methods are used to apply properties of shapes to solve real problems.