Properties of shape - Vocabulary

Geometry for Year 3 students encompasses a wide range of vocabulary terms related to shapes and their properties. A 2-D shape, such as a triangle, circle, square, rectangle, pentagon, or hexagon, is flat and cannot be picked up. These shapes are defined by their sides and vertices (the plural of vertex), which are the points where the sides meet. A corner is specifically the point where the sides of a 2-D shape meet. In contrast, 3-D shapes like cylinders, cuboids, cubes, tetrahedrons, spheres, and square-based pyramids are three-dimensional and can be physically picked up. These shapes have faces, which are their flat surfaces, and edges, where two faces intersect. Understanding the orientation of a shape is important, as it refers to the position in which the shape is presented, and this can vary without changing the shape's fundamental properties.

Shapes can also be classified by their symmetry. A symmetrical shape has matching sides that align perfectly when folded in half, while non-symmetrical shapes do not. Polygons are 2-D shapes with straight sides, and when a shape has a vertical line of symmetry, it is divided into equal parts by a line that runs up and down. In the realm of angles, students learn about right angles, which are exactly 90 degrees, acute angles, which are smaller than right angles, and obtuse angles, which are larger. Understanding turns is also crucial; a quarter turn is equivalent to one right angle, a half turn to two, a three-quarter turn to three, and a full turn to four right angles. Turns can be made clockwise or anti-clockwise. Finally, lines can be horizontal, running left to right, vertical, running up and down, or perpendicular, meeting at a right angle.