Lesson Notes By Weeks and Term v4 - SHS 2

SPATIAL SENSE

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Subject: Mathematics

Class: SHS 2

Term: 2nd Term

Week: 3

Grade code: 2.3.1.LI.3

Strand code: 3

Sub-strand code: 1

Content standard code: 2.3.1.CS.1

Indicator code: 2.3.1.LI.3

Theme: GEOMETRY AROUND US

Subtheme: SPATIAL SENSE

Lesson Video

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Performance objectives

Define rotational symmetry and identify shapes that have it.
Determine the order and angle of rotational symmetry.
Perform rotations of points and shapes on the coordinate plane.
Identify rotational symmetry in real-life examples.

Lesson summary

This lesson introduces the concept of rotational symmetry and the transformation of rotation on the Cartesian plane. We see rotation everywhere around us in Ghana—from the beautiful patterns in Adinkra symbols and Kente cloth to the spinning wheels of a tro-tro and the blades of a ceiling fan. Understanding rotation helps us appreciate the geometry in our culture and environment and is a fundamental skill in fields like engineering, graphic design, and architecture. Today, we will explore how shapes can look the same after being turned and how to mathematically describe this turning process on a graph.

Lesson notes

Part A: Rotational Symmetry

Definition: Rotational Symmetry is a property a shape has when it looks exactly the same after being rotated (turned) less than a full 360°. The shape must fit perfectly onto its original outline. Centre of Rotation: The fixed point around which the shape is turned. For most regular polygons, this is the centre of the shape. Order of Rotational Symmetry: The number of times a shape fits exactly onto its original position during one full 360° turn. Angle of Rotation: The smallest angle you need to turn the shape for it to look the same as it did at the start.

Relationship between Order and Angle: There is a simple formula that connects the order and the angle of rotation: Angle of Rotation = 360° / Order of Rotational Symmetry

Worked Examples:

Evaluation guide

Identify shapes with rotational symmetry and show the image of an object (or point)
after a rotation about the origin (or point).
Think -pair share activities : Learners in pairs research and make presentations on the concept of
rotational symmetry in Mathematics.