Cubes, Cuboids and Cylinders as Three-Dimensional Shapes for Primary 4

Three dimensional shapes

Performance Objectives

By the end of the lesson, students should be able to:

1. distinguish between open and closed shapes;
2. identify the uses of three-dimensional shapes.

Understanding Shapes

Shapes are all around us. Everything we see and touch has a shape. Some shapes are flat, like a drawing on paper, while others are solid and take up space.

What Are Three-Dimensional Shapes?

Three-dimensional shapes are solid shapes that have length, width, and height. They are also called 3D shapes. These shapes can be held and they take up space.

Imagine a ball, a box, or a tin of milk. These are all examples of three-dimensional shapes because they are solid and have thickness or depth.

Open and Closed Shapes

Shapes can be described as either open or closed. This helps to understand how different shapes are formed.

Meaning of Open Shapes

An open shape is a shape that does not have a continuous boundary. It has a starting point and an ending point that do not meet.

Think of a letter ‘C’ or a line drawn on paper that does not connect back to itself. These are open shapes.

Meaning of Closed Shapes

A closed shape is a shape that has a continuous boundary. It starts and ends at the same point, forming a complete outline.

Examples of closed shapes include a circle, a square, or a triangle. They have no gaps in their boundaries.

Three-dimensional objects can also be thought of as open or closed. For example, a sealed carton is a closed three-dimensional object. A bucket or an open milk tin is an open three-dimensional object because it has an opening at the top.

Common Three-Dimensional Shapes

Many objects around us have common three-dimensional shapes. Some of these shapes are cuboids, cubes, and cylinders.

Cuboids

A cuboid is a three-dimensional shape that has six flat faces. All its faces are rectangles. Opposite faces of a cuboid are identical.

Examples of cuboids include:

1. A shoebox
2. A brick
3. A book
4. A carton of milk

Cubes

A cube is a special type of cuboid where all six faces are identical squares. This means all the sides of a cube are equal in length.

Examples of cubes include:

1. A dice (singular of dice)
2. A sugar cube
3. Some building blocks

Cylinders

A cylinder is a three-dimensional shape that has two flat circular faces at its ends and one curved surface connecting them. The two circular faces are identical and parallel to each other.

Examples of cylinders include:

1. A tin of Milo or milk
2. A water tank
3. A bucket
4. A battery

Uses of Three-Dimensional Shapes

Three-dimensional shapes are used in many ways in our daily lives. They are important for building, storing, and packaging objects.

The uses of these shapes include:

1. Storage: Cuboids (like cartons and boxes) and cylinders (like tins and buckets) are used to store food, drinks, clothes, and many other items. Their solid shapes allow them to hold things inside.
2. Construction: Cuboids (like bricks and blocks) are fundamental in building houses, walls, and other structures. Their stable shape makes them good for stacking.
3. Packaging: Many products are packaged in cuboid or cylindrical containers to protect them and make them easy to transport. Examples include cereal boxes, juice cartons, and canned foods.
4. Play and Learning: Cubes are often used in games (like dice) and in educational toys (like building blocks) because of their simple, balanced form.
5. Transporting Liquids: Cylindrical shapes like water tanks and buckets are excellent for holding and transporting liquids because their curved surfaces are strong and easy to handle.
6. Everyday Objects: Many common objects have these shapes, such as refrigerators (cuboid), batteries (cylinder), and books (cuboid).