Lesson Notes By Weeks and Term v5 - Grade 5

Lesson Video

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Performance objectives

• Identify and name common 2D shapes and 3D objects.
• Describe the properties of 2D shapes (sides, angles).
• Describe the properties of 3D objects (faces, edges, vertices).
• Tell the difference between 2D shapes and 3D objects.
• Draw 2D shapes and identify 3D shapes from pictures.

Lesson summary

Geometry is all around us! From the shapes of our houses to the patterns in our traditional Ndebele art, understanding shapes and objects is crucial. In this week's lesson, we'll focus on the properties of 2D shapes (like squares and circles) and 3D objects (like cubes and spheres). Recognizing these properties will help you understand the world better and solve problems in everyday life, such as calculating how much paint you need to cover a wall or understanding how a soccer ball is made. Knowing these concepts will also help you in other subjects like arts and technology!

Lesson notes

2D Shapes (Two-Dimensional) 2D shapes are flat shapes that only have length and width. Think of them as drawings on a piece of paper. Here are some key 2D shapes and their properties: Square: Sides: 4 sides Angles: 4 right angles (90 degrees each)

Properties: All sides are equal in length. Opposite sides are parallel. Adjacent sides are perpendicular.

Example: A checkerboard square, some windows.

Rectangle: Sides: 4 sides Angles: 4 right angles (90 degrees each)

Properties: Opposite sides are equal in length. Opposite sides are parallel. Adjacent sides are perpendicular.

Example: A door, a book, a blackboard.

Triangle: Sides: 3 sides Angles: 3 angles (sum of angles is 180 degrees)

Properties: Triangles can be different types (equilateral, isosceles, scalene, right-angled). An equilateral triangle has three equal sides and three equal angles.

Example: The roof of a house, a yield sign.

Circle: Sides: A curved line that never ends Angles: A circle does not have angles.

Properties: All points on the circle are the same distance from the center.

Example: A wheel, the sun, a plate.

Parallel Lines: Two lines are parallel if they never meet, no matter how far they are extended. Think of train tracks.

Perpendicular Lines: Two lines are perpendicular if they meet at a right angle (90 degrees). 3D Objects (Three-Dimensional) 3D objects are solid shapes that have length, width, and height. They take up space.

Cube: Faces: 6 square faces Edges: 12 edges Vertices: 8 vertices (corners)

Properties: All faces are squares and are the same size.

Example: A dice, some boxes.

Rectangular Prism (Cuboid): Faces: 6 rectangular faces Edges: 12 edges Vertices: 8 vertices (corners)

Properties: All faces are rectangles. Opposite faces are the same size.

Example: A brick, a shoebox.

Sphere: Faces: 1 curved surface Edges: 0 edges Vertices: 0 vertices Properties: All points on the surface are the same distance from the center.

Example: A soccer ball, a marble, the earth.

Cylinder: Faces: 2 circular faces and 1 curved surface Edges: 2 edges Vertices: 0 vertices Properties: Two parallel circular bases connected by a curved surface.

Example: A can of beans, a toilet roll. Faces, Edges, and Vertices Faces: The flat surfaces of a 3D object.

Edges: The lines where two faces meet.

Vertices: The corners where edges meet. (Singular: Vertex)

Worked example

Identifying a Shape: Thando sees a sign that has three sides and three angles. What shape is it?

Solution: A triangle.

Counting Faces: Lindiwe is playing with a building block that has 6 square faces. How many faces does the block have? What shape is it?

Solution: It has 6 faces. It is a cube.

Describing a Rectangle: Sipho is drawing a rectangle. What can you say about its sides and angles?

Solution: A rectangle has 4 sides and 4 right angles. Opposite sides are equal in length and parallel. Adjacent sides are perpendicular.

Distinguishing 2D and 3D: Maryam is holding a soccer ball. Jabu is drawing a circle. What is the difference between what Maryam is holding and what Jabu is drawing?

Solution: Maryam is holding a sphere (3D object), which is solid and takes up space. Jabu is drawing a circle (2D shape), which is flat and only has length and width.

Guided Practice (With Solutions)

Question 1:

Look at the following shape: [Imagine a drawing of a square]

a) What is the name of the shape?

b) How many sides does it have?

c) Are all sides equal in length?

Solution: