Identify faces of three-dimensional figures
Key Notes :
Three-Dimensional (3D) Figures
- 3D figures have length, width, and height.
- Examples include cube, cuboid, cylinder, cone, sphere, and pyramid.
What is a Face?
- A face is a flat or curved surface of a 3D figure.
- Flat faces are usually in the shape of polygons like squares or rectangles.
- Curved faces are round, like the surface of a ball or cylinder.
Number of Faces in Common 3D Figures
| Figure | Type of Faces | Number of Faces |
|---|---|---|
| Cube | Flat (Squares) | 6 |
| Cuboid | Flat (Rectangles) | 6 |
| Cylinder | 2 Flat (Circles), 1 Curved | 3 |
| Cone | 1 Flat (Circle), 1 Curved | 2 |
| Sphere | Curved only | 1 |
| Square Pyramid | 1 Square base, 4 Triangle faces | 5 |
Faces Help Identify Shapes
- By counting and examining the type and shape of the faces, students can name the 3D figure.
Hands-On Learning
- Use building blocks or paper models to let students feel and count the faces.
Face vs Surface
- All faces are surfaces, but not all surfaces are flat.
- Curved surfaces like that of a sphere are also called surfaces but not flat faces.
Learn with an example
🎯 Does this shape have a square as a face?
- yes
- no
The shape is a cylinder.
The two faces of a cylinder are circles. The rest of the surface is curved. Here is one face.
So, the correct answer is no. A cylinder does not have a square as a face.
🎯 Does this shape have a square as a face?
- yes
- no
The shape is a cone.
The only face of a cone is a circle. The rest of the surface is curved. Here is the face.
So, the correct answer is no. A cone does not have a square as a face.
🎯 Does this shape have a triangle as a face?
- yes
- no
The shape is a cylinder.
The two faces of a cylinder are circles. The rest of the surface is curved. Here is one face.
So, the correct answer is no. A cylinder does not have a triangle as a face.
let’s practice!
