📘 Three Dimensional Shapes - Page 6 Explanation
📖 Open your textbook page number 6.
This page explains Cone, Sphere, and the Discuss questions.
🔺 Cone
A cone is a three-dimensional shape. It has a pointed top and a circular bottom. The pointed top is called the vertex.
📍 Vertex
🌀 Curved surface
⭕ Circular edge
⭕ Circular face
✂️ Activity
(1) Draw a circle with a radius of 6 cm on a piece of paper.
(2) Cut the circle with scissors. Cut out two semicircles from it.
(3) Glue the two radii of a semicircle together.
(4) Draw another circle with radius 3 cm on the paper. Cut it out and stick it on the circumference of the shape you have made.
(5) The three-dimensional shape formed is a cone.
(6) Write the elements of a cone.
In this activity, students make a cone using paper. First, they draw a big circle of radius 6 cm. Then they cut it and make semicircles.
After that, the two straight sides, called radii, of one semicircle are glued together. When the radii are joined, the semicircle becomes a pointed shape. This forms the curved part of a cone.
Then a smaller circle of radius 3 cm is cut and fixed at the bottom. This small circle becomes the circular face of the cone.
“The three-dimensional shape formed is a cone.”
🧩 Elements of a Cone
The textbook asks us to write the elements of a cone.
- 📍 Vertex: The pointed top of the cone.
- ⭕ Circular edge: The round boundary where the curved surface and circular face meet.
- ⭕ Circular face: The flat circular bottom of the cone.
- 🌀 Curved face: The curved side surface of the cone.
📍 1 Vertex
⭕ 1 Circular edge
⭕ 1 Circular face
🌀 1 Curved face
⚽ Sphere
“We see shapes like ball and ladoo in our daily life. The shape of a ball is spherical. This three-dimensional figure does not have edges and vertices, but has a curved surface.”
A sphere is a round three-dimensional shape. A ball and a ladoo are examples of spherical shapes.
A sphere has no flat face, no edge, and no vertex. It has only one curved surface.
⚽ A sphere has no edges.
⚽ A sphere has no vertices.
⚽ A sphere has one curved surface.
💬 Discuss
(2) “Can the height of a three-dimensional shape sphere be shown?”
✅ Answer 1
The height of a prism, pyramid, cylinder, and cone can be shown by drawing a straight vertical line from the top to the bottom.
This line tells us how tall the shape is.
✅ Answer 2
The height of a sphere cannot be shown in the same way as a prism, pyramid, cylinder, or cone. A sphere is round from all sides and has no top face or bottom face.
So, for a sphere, we usually talk about its diameter, not height.
📝 Practice Set 1.1
📖 Now look at the Practice Set 1.1 given at the bottom of page 6.
The textbook asks: “Complete the table below.”
A prism has 2 bottom/top faces, but a pyramid has only 1 bottom face. The number of vertical faces is the same as the number of sides of the bottom face.
🌟 Page Summary
- 📦 A prism has two equal bottom/top faces.
- 🔺 A pyramid has only one bottom face.
- 📍 We completed the table of triangular, square, and pentagonal prisms and pyramids.
- 📏 We learned how to count vertices, edges, vertical faces, and bottom/top faces.
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