Toy Joy Chapter Notes | Mathematics for Class 3 (Maths Mela) PDF Download

Introduction

Imagine looking around your room right now. You'll see so many cool things, right?

• A round ball
• A rubik's cube and so many more different shapes.

These Shapes are called 3D shapes. 

Now, What are 3D Shapes?

They're like the shapes you can touch and hold, not just flat like a drawing on paper. Let's dive into some examples:

• Cube: Think of a dice or a Rubik's Cube. It's like a solid box with six square faces.
• Sphere: Picture a ball or an orange. It's completely round, like a basketball.
• Cylinder: Imagine a can of soda or a flashlight. It's like a tube with two circular faces.
• Cone: Think of an ice cream cone or a party hat. It's like a triangle that curves up to a point.

Let's have a look at some 3D Shapes:

Now that we know what different 3D shapes looks like, Let's understand more.

Let's Understand with Story

Once upon a time, there lived a curious boy named Kunaal. He had just learned all about different 3D shapes in his school, and he was excited to share this newfound knowledge with his little sister, Ayushi. Kunaal knew that learning about shapes could be so much fun, especially when you can see them all around you.

• One sunny afternoon, Kunaal called out to Ayushi, "Hey Ayushi, come with me! I want to show you something really cool." Ayushi, always happy to learn from her big brother, quickly joined him.
• Kunaal took Ayushi on a tour around their house. "Look, Ayushi," Kunaal said with a smile, "see that box of building blocks? It's shaped like a cube!"
  
• Next, they went to the kitchen, where Kunaal pointed at a cereal box. "This is a cuboid," he explained. "It's like a stretched-out cube with rectangular faces. See how it's longer than it is wide?"
  
• As they moved to the living room, Kunaal spotted a party hat from Ayushi's recent birthday celebration. "Look at this cone," he exclaimed. "It's like a triangle that's getting narrower as it goes up. Remember the ice cream cones we love?"
  
• In the garden, Kunaal picked up a ball. "This is a sphere," he said, rolling it in his hands. "It's completely round, just like a basketball."
  
• Finally, they went to the garage, where Kunaal showed Ayushi a flashlight. "See this cylinder! It's like a can of soda or a tube. It has two circular faces and a curved surface."
  
• Ayushi was amazed at how many shapes they could find right in their own home. "Thank you, Kunaal Bhaiya," she said happily. "Now I understand 3D shapes, all thanks to you!"
  

Kunaal was happy and proud to have shared his knowledge with his sister. From that day on, whenever they played or explored, Ayushi would point out different shapes.

More About 3D Shapes

Shapes have different parts, let's explaore them:

• Face: In geometry, a face is a flat surface on a 3D shape. Think of it like the side of a box or a piece of paper. Faces are what you see when you look at a shape from different angles. For example, if you look at a cube, each of its six sides (which are all squares) is a face.
• Edge: An edge is like a line segment that connects two vertices (corners) of a shape. It's where two faces meet. Imagine the edges of a cube—it's the lines where the square faces come together.
• Corner (Vertex): A corner, also called a vertex, is a point where edges meet. It's like the tip of a pyramid or the corner of a room. If you take a cube, each of its eight corners is where three edges meet.
  

Now, let's apply these definitions to the shapes you're interested in:

1. Cube:

Cube

• Faces: A cube has 6 square faces.
• Edges: A cube has 12 edges, which are the lines where two faces meet.
• Corners (Vertices): A cube has 8 corners where three edges meet.

2. Cuboid:

Cuboid

• Faces: Like a cube, a cuboid also has 6 faces, but they are rectangles (or squares if all sides are equal).
• Edges: A cuboid has 12 edges, similar to a cube.
• Corners (Vertices): A cuboid has 8 corners where three edges meet.

3. Cone:

Cone

• Faces: A cone has 2 faces—a circular base and a curved surface that meets at the top.
• Edges: It has one curved edge that forms the surface and one straight edge at the base.
• Corners (Vertices): A cone has one corner, called the vertex, at the top where the curved surface and base meet.

4. Sphere:

Sphere

• Faces: A sphere doesn't have any flat faces! It's like a perfectly round ball.
• Edges: There are no edges on a sphere because it's smooth all around.
• Corners (Vertices): Since it has no flat faces, a sphere also has no corners or vertices.

5. Cylinder:

Cylinder

• Faces: A cylinder has 3 faces—a circular top, a circular bottom, and a curved surface.
• Edges: A cylinder has two edges—one around the circular top and one around the circular bottom, plus one curved edge for the side.
• Corners (Vertices): A cylinder has two corners, one at each end (top and bottom).