📘 Three-Dimensional Shapes - Page 3 Explanation

📖 Open your textbook page number 3.
This page explains two dimensional shapes, three dimensional shapes, and polygons in a simple way.

📄 Two Dimensional Shapes

A two dimensional shape is a flat shape. It has only one surface. We can draw it on paper. It does not have thickness or height.

In a 2D shape, a vertex means a corner. For example, in a triangle, two sides meet at one corner. That corner is called a vertex.

A side means a straight line forming the boundary of a shape. In a square, all four boundary lines are sides.

🧊 Three Dimensional Shapes

A three dimensional shape is a solid shape. We can hold it in our hand. It has length, width, and height.

In a 3D shape, a face means a flat surface. For example, a box has a front face, back face, top face, bottom face, left face, and right face.

An edge is the line where two faces meet. For example, in a box, the top face and front face meet at one line. That line is an edge.

A vertex in a 3D shape is a corner where three or more edges meet. For example, the corner of a box is a vertex.

🔍 Easy Difference Between 2D and 3D Shapes

📄 Two Dimensional Shapes	🧊 Three Dimensional Shapes
Flat shapes	Solid shapes
Can be drawn on paper	Can be held or touched as objects
Have only one surface	Have many surfaces
Have sides and vertices	Have faces, edges, and vertices

📐 Polygon

A polygon is a closed flat shape made with straight sides. Closed means there should be no gap in the shape.

A polygon must have at least three sides. So, a triangle is the smallest polygon. A circle is not a polygon because it does not have straight sides.

✅ Complete the Table Below

Name	Number of Vertices	Number of Sides
🔺 Triangle	3	3
▱ Quadrilateral	4	4
⬟ Pentagon	5	5
⬡ Hexagon	6	6
⬣ Heptagon	7	7
🔷 Octagon	8	8

🤔 Think About

If we keep increasing the number of sides of a polygon, the shape slowly starts looking like a circle. So, the closed figure formed will look like a circle.

🧪 Do it

Students can use straws or sticks as sides. They can join them to form closed shapes. For example, 3 sticks can make a triangle, 4 sticks can make a quadrilateral, and 5 sticks can make a pentagon.