In geometry we know that basic shapes contain flat figures and solid figures.

**Difference between square and rectangle:** Square has all sides the same and rectangle has opposite sides the same.

**Region enclosed between the two circles:**

When two circles cross

**Airplane figure:** The figures lying in the plane are called flat figures.

For example square, rectangle, triangle, diamond and circle. They are also called flat shapes.

**Square:** It has 4 sides and 4 corners. The area enclosed inside is called the square area.

**Rectangle:** It has 4 sides and 4 corners and the area enclosed in it is called the rectangular area.

**Triangle:** It has 3 sides and 3 corners or corners. The area enclosed within the triangle is called the triangle region.

**Diamond:** It has 4 sides and 4 corners and the enclosed area is called the diamond region.

**Circle:** It has no sides and no corners. The area enclosed within the circle is called the circular area.

The area enclosed between the two circles is indicated by the shaded area.

When one circle is inside the other

The area enclosed between the two circles is indicated by the shaded area.

**Solid numbers:** We know some of the geometric shapes such as cuboids, cubes, cylinders, cones, spheres, triangular prisms, etc. These are called solid figures or solids. They are also known as three-dimensional (3-D) figures. They take up space. In real life, many objects seen in our environment take the form of one or more of the above mentioned solids.

Third grade geometry lessons encourage children to develop the basic concept to expand their knowledge of geometry.

Faces of the solid: the two types of surfaces such as flat surfaces, curved surfaces.

Common solid figures: some of the solid shapes like cube, cuboid, cylinder, cone, sphere.

**Important points about basic geometric shapes:**

We learned about solid shapes and flat shapes. Let’s remember some important points about shapes.

**1.** Solid objects have different shapes such as cubes, cuboids, cylinders, cones and spheres.

**2.** Solids have two types of surfaces; flat surfaces and curved surfaces. Objects like books, matchboxes and rulers have flat surfaces, while objects like soccer ball, apple, watermelon have curved surfaces.

**3.** Flat shapes are made up of straight or curved lines. Rectangle, circle, square, triangle are flat shapes.

**Questions and answers about basic forms:**

**1. Choose the right shapes:**

**(I)**

(a) cone; (b) cylinder; (c) sphere; (d) dice

**(ii) **

(a) cone; (b) cylinder; (c) sphere; (d) dice

**(iii) **

(a) cone; (b) cylinder; (c) sphere; (d) cuboid

**(iv) **

(a) cone; (b) cylinder; (c) sphere; (d) dice

**(v) **

**Reply:**

**1.** (I) → (a)

(ii) → (c)

(iii) → (d)

(iv) → (b)

(v) → (d)

**2. Choose the correct answer:**

**I.** The shape of the base of a cuboid is a ……

(i) circle

(ii) rectangle

(iii) square

**II. **The shape of the bracelet is like a …….

(i) circle

(ii) triangle

(iii) square

**III. **The shape of a postcard is like a …….

(i) circle

(ii) rectangle

(iii) square

**IV.** The shape of the bottom of a matchbox is like a ……

(i) circle

(ii) triangle

(iii) rectangle

**V. **The shape of the bottom of a bucket is like a ……

(i) circle

(ii) triangle

(iii) rectangle

**Reply:**

**2. **I → (ii)

II → (I)

III → (ii)

IV → (iii)

V → (I)

**3. Trace and colour the rocket. Answer the following questions.**

My missile has

(i) _____ circles

(ii) _____ rectangles

(iii) _____ squares

(iv) _____ triangles

**Reply:**

**3.** (i) 2 circles

(ii) 1 rectangle

(iii) 2 squares

(iv) 5 triangles

**Related concepts**

**● ****Surfaces of solids**

**● ****Common solid figures**

**● ****Points, lines and shapes**

**● ****Line segment, ray and line**

**● ****Types of lines**

**● ****Geometric design and models**

**3rd grade math class**

**From the basic forms to the HOME**

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