Glossary

As your child's knowledge progresses it becomes important to start using proper terminology when describing shapes and objects. Some commonly used vocabulary and their meaning are below.

2D Shapes

Circle

A 2D shape made by drawing a curve that is always the same distance from the centre.

Properties:

1 continuous side
No corners

Square

A 2D shape with straight sides of all equal length.

Properties:

4 sides
4 corners (all right angles internally)

Triangle

A 3-sided 2D shape with all straight sides. Types of triangles include equilateral, right-angle, isosceles and scalene.

Properties:

3 sides
3 corners

Rectangle

A 2D shape with straight sides, where opposite sides are parallel and equal length.

Properties:

4 sides
4 corners (all right angles internally)

Rhombus

A 2D shape with all equal straight sides, where the opposite angles are equal.

Properties:

4 sides
4 corners

Parallelogram

A 2D shape where the opposite straight sides are parallel and equal in length. The opposite corner angles are also equal.

Properties:

4 sides
4 corners

Trapezoid

A 2D shape made up of 4 straight sides, where at least one pair of opposite sides are parallel.

Properties:

4 sides
4 corners

Oval

A curved egg or ellipse 2D shape. Oval shapes can be varied.

Properties:

1 continuous side
No corners

Pentagon

A 5 sided polygon.

Properties:

5 sides
5 corners

Hexagon

A 6 sided polygon.

Properties:

6 sides
6 corners

Heptagon

A 7 sided polygon.

Properties:

7 sides
7 corners

Octagon

An 8 sided polygon.

Properties:

8 sides
8 corners

3D Objects

Sphere

A 3D object shaped like a ball.

Properties:

1 face
No edges
No vertices

Cube

A box-shaped solid object that has six identical square faces.

Properties:

6 faces
12 edges
8 vertices

Cuboid

Also called a rectangular prism. It is a boxed-shaped object, where all faces are rectangles.

Properties:

6 faces
12 edges
8 vertices

Cone

A 3D object with a circular base, joined to a point by a curved side.

Properties:

2 faces
1 edge
1 vertice

Cylinder

A solid object opposite identical circular flat ends joined by a curved side.

Properties:

3 faces
2 edges
No vertices

Square-Based Pyramid

An object where the sides are triangles which meet at the top, with a square shapes base.

Properties:

5 faces
8 edges
5 vertices

Triangle-Based Pyramid

Also called a tetrahedron, where the sides are triangles which meet at the top, with a triangle base.

Properties:

4 faces
6 edges
4 vertices

Octahedron

A polyhedron with 8 faces.

Properties:

8 faces
12 edges
6 vertices

Triangular Prism

A prism with the cross section of a triangle

Properties:

5 faces
9 edges
9 vertices

Pentagonal Prism

A prism with the cross section of a pentagon

Properties:

7 faces
15 edges
10 vertices

Hexagonal Prism

A prism with the cross section of a hexagon.

Properties:

8 faces
18 edges
12 vertices

Dodecahedron

A polyhedron with 12 flat faces.

Properties:

12 faces
30 edges
20 vertices

Key Terms

Shape

A geometric object, which can be seen in two-dimensional space (square, triangle, circle) or three-dimensional space (sphere, pyramid, cube)

Side

A line segment of a flat shape

Corner

The point at which two sides meet

Parallel

Lines on a plane that never meet, remaining the same distance apart.

Solid/Structure

A geometric object that contains the three dimensions of width, height and depth (cube, sphere, pyramid)

Face

A flat surface of a 3D solid/object, or a continuous curved surface

Edge

The line segment formed by the joining of two faces

Vertex/Vertices

The point at which several edges meet, and do not extend beyond (point of a cone, corner of a cube)

Polygon

A 2D shape with straight sides

Polyhedron

A 3D solid where all faces are polygons

Prism

A polyhedron with two identical and parallel polygonal bases

Net

A pattern that you can cut and fold to make a model of a solid shape.

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