Lesson Notes By Weeks and Term v5 - Grade 5

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Identify and describe properties of 2D shapes.
• Identify and describe properties of 3D objects.
• Tell the difference between 2D shapes and 3D objects.
• Use geometry vocabulary correctly.
• Recognize shapes and objects in the real world.

Lesson summary

Geometry is all around us! From the shape of your classroom to the design of the houses in your neighbourhood, geometry helps us understand and describe the world. In Grade 5, we are building on what you already know about shapes and objects to describe them more precisely. This week, we'll focus on understanding the properties of different 2D shapes (like squares, triangles, and circles) and 3D objects (like cubes, spheres, and pyramids). Understanding these shapes and objects is important for many things in life, from packing a suitcase efficiently to understanding the designs of buildings and bridges you see around South Africa.

Lesson notes

2D Shapes: Properties and Definitions 2D shapes are flat shapes that only have length and width.

Let's explore some common ones: Square: A square has four sides that are all equal in length. It also has four right angles (90°). A square has 4 lines of symmetry. This means you can fold it in half four different ways and the two halves will match perfectly.

Rectangle: A rectangle has four sides. Opposite sides are equal in length and parallel to each other. It also has four right angles (90°). A rectangle has 2 lines of symmetry. Parallel means that lines will never meet, no matter how far you extend them. Think of train tracks - they run parallel to each other.

Triangle: A triangle has three sides and three angles.

There are different types of triangles: Equilateral Triangle:* All three sides are equal in length, and all three angles are equal (60° each). It has 3 lines of symmetry.

Isosceles Triangle:* Two sides are equal in length, and two angles are equal. It has 1 line of symmetry.

Scalene Triangle:* No sides are equal in length, and no angles are equal. It has 0 lines of symmetry.

Right-angled Triangle:* One angle is a right angle (90°).

Circle: A circle is a round shape with no corners or straight sides. All points on the circle are the same distance from the center. It has infinite lines of symmetry.

Radius:* The distance from the center of the circle to any point on the circle.

Diameter:* The distance across the circle, passing through the center. The diameter is twice the length of the radius.

Symmetry:* A shape has symmetry if you can draw a line through it and the two halves match perfectly. That line is called the line of symmetry.

Example 1: Draw a square and label its sides as 5cm each. Calculate the perimeter.

Solution: A square has 4 equal sides. The perimeter is the total length of all the sides.

Therefore, the perimeter is 5cm + 5cm + 5cm + 5cm = 20cm Example 2: A rectangle has a length of 8cm and a width of 3cm. What is its perimeter?

Solution: A rectangle has two sides of the same length (8cm) and two sides of the same width (3cm). The perimeter is 8cm + 8cm + 3cm + 3cm = 22cm 3D Objects: Properties and Definitions 3D objects (also called solids) have length, width, and height (or depth).

Let's look at some common ones: Cube: A cube has six square faces. All faces are equal in size. It has 12 edges (where the faces meet) and 8 vertices (corners).

Rectangular Prism: A rectangular prism has six rectangular faces. Opposite faces are equal in size. It also has 12 edges and 8 vertices. Think of a brick or a shoebox.

Sphere: A sphere is a round object, like a ball. All points on the surface of the sphere are the same distance from the center. It has no faces, edges, or vertices.

Pyramid: A pyramid has a base that is a polygon (like a square or a triangle) and triangular faces that meet at a point called the apex. A square pyramid has a square base and four triangular faces. It has 5 faces, 8 edges, and 5 vertices.

Cylinder: A cylinder has two circular faces and a curved surface. It has two edges and no vertices. Think of a tin can.

Cone: A cone has one circular face and a curved surface that tapers to a point (the apex). It has one edge and one vertex. Think of an ice cream cone.

Face:* A flat surface on a 3D object.

Edge:* The line where two faces meet.

Vertex (plural: Vertices):* The point where two or more edges meet (a corner).

Example 3: Imagine a building block that is a cube. How many faces, edges and vertices does it have?

Solution: A cube has 6 faces, 12 edges and 8 vertices.

Example 4: A pyramid has a square base. How many triangular faces does it have?

Solution: It has 4 triangular faces. Differentiating between 2D and 3D The main difference between 2D shapes and 3D objects is that 2D shapes are flat and only have length and width, while 3D objects have length, width, and height. 2D shapes can be drawn on a piece of paper, while 3D objects take up space in the real world. Guided Practice (With Solutions)

Question 1: Identify the shape: It has three sides, and all its sides are equal. What is it?

Solution: This is an equilateral triangle. It has three sides, and because all sides are equal, it is an equilateral triangle.

Question 2: Identify the object: It has six faces that are all rectangles, but not all the faces are squares. What is it?

Solution: This is a rectangular prism. Because all the faces are rectangles (and not all squares), it cannot be a cube.

Question 3: How many faces, edges and vertices does a square pyramid have?

Solution: A square pyramid has: 5 faces (1 square base and 4 triangles) 8 edges 5 vertices Question 4: True or False: A cylinder has vertices.

Solution: False. A cylinder has no vertices. It has two circular faces and a curved surface. Independent Practice (Questions Only) Draw a rectangle and label its sides 7cm and 4cm. Calculate the perimeter. Name three objects you might find in your kitchen that are cylinders. A triangular prism has 5 faces.