Year 2 Children will be taught to identify properties of shapes such as the number of sides and vertices corners. Children will count the number of sides and corners on the shape. They will describe shapes using the properties, for example: This shape has 3 corners and 3 sides.
What is the shape? Year 3 Children will extend their knowledge of polygons to include different types of triangles and quadrilaterals. They will be introduced to heptagons, nonagons and decagons. Knowledge of shape properties will include angles and symmetry of these polygons. Children will describe shapes and identify them using their properties including symmetry and angles.
They might be asked to sort shapes according to their properties using Venn diagrams and Carroll diagrams. Year 4 Children are taught to compare lengths and angles of polygons to decide if they are regular or irregular. Children will be given a range of polygons to sort into regular and irregular; this might be be completing practical tasks or using ICT. Year 5 Children will be taught to distinguish between regular and irregular polygons based on reasoning about equal sides and angles.
The following figure is not a polygon as it is not a closed figure. Polygons are named according to the number of sides. The names of the most common polygons are given below:. If a polygon has a reflex angle , then it is said to be a concave polygon. If a polygon has no reflex angle , then it is said to be a convex polygon. Understanding shapes is important in mathematics. You will certainly be required to learn about shapes at school but understanding the properties of shapes has many practical applications in professional and real-life situations too.
Many professionals need to understand the properties of shapes, including engineers, architects, artists, real-estate agents, farmers and construction workers. You may well need to understand shapes when doing home improvements and DIY, when gardening and even when planning a party. A three-sided polygon is a triangle.
There are several different types of triangle see diagram , including:. Triangles can also be described in terms of their internal angles see our page on Angles for more about naming angles. A triangle with only acute internal angles is called an acute or acute-angled triangle. One with one obtuse angle and two acute angles is called obtuse obtuse-angled , and one with a right angle is known as right-angled.
Each of these will also be either equilateral, isosceles or scalene. Four-sided polygons are usually referred to as quadrilaterals, quadrangles or sometimes tetragons.
In geometry the term quadrilateral is commonly used. The term tetragon is consistent with polygon, pentagon etc. You may come across it occasionally, but it is not commonly used in practice. Parallelogram : Opposite sides are parallel, opposite sides are equal in length, opposite angles are equal.
Rhombus : A special type of parallelogram in which all four sides are the same length, like a square that has been squashed sideways. Trapezium or trapezoid : Two sides are parallel, but the other two sides are not. What is a Polygon? The word " polygon " means "many-angled," from Greek. To be a polygon, a flat, closed shape must use only line segments to create its sides.
So a circle or any shape that has a curve is not a polygon. The family of complex star-shaped polygons generally share the Greek number prefix and use the suffix -gram: pentagram, hexagram, octagram, and so on. What you learned: After viewing the video, reading these notes, and studying the drawings, you will learn to: Define a polygon Recognize its identifying properties Distinguish between regular and irregular polygons, simple and complex polygons, and concave and convex polygons Draw and recognize examples of all the types of polygons.
Instructor: Malcolm M. Malcolm has a Master's Degree in education and holds four teaching certificates. He has been a public school teacher for 27 years, including 15 years as a mathematics teacher.
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