# GM3-3: Classify plane shapes and prisms by their spatial features.

Elaboration on this Achievement Objective

This means students will be able to define the characteristics of things and use these characteristics as a basis for sorting. Plane figures are those that lie flat, so have only two dimensions. So circles, triangles, and hexagons are all plane shapes. At Level Three students should be able to classify plane shapes by the following characteristics: number of sides and angles (for example all triangles have three sides), parallel or non-parallel sides (for example a trapezium has one pair of parallel sides), equal or unequal side length, angle size (less than, equal to, greater than a right angle), lines of mirror symmetry and order of rotational symmetry (for example a square maps onto itself four times in a full turn). Prisms are solid shapes that have a fixed cross-section. A loaf of bread can be seen as a rectangular prism since the slices are the same rectangle. So prisms are classified by their cross-section, for example a triangular prism has triangular cross-sections. In this way a cylinder can be seen as a type of prism though its cross-section is a circle.