Class 3 Notes - Geometry

Download PDF Worksheets
Start a Practice Test

1. Introduction to Geometry

Geometry is the study of shapes, figures, and the space around us. In Class III, children learn the basics of geometry: lines, curves, shapes, patterns, and simple properties of figures.

Geometry is everywhere: in classrooms, playgrounds, toys, books, and even in the sun and moon. It helps children observe the world mathematically.

  • Recognize basic shapes and figures.
  • Understand lines, curves, open and closed figures.
  • Differentiate between 2-D (flat) and 3-D (solid) shapes.
  • Identify corners (vertices), sides, edges, and faces.
  • Relate geometry to everyday objects.

2. Lines and Curves

2.1 Line

A line is a straight path that goes on endlessly in both directions.

Examples: edge of a ruler, string pulled tightly, border of a book.

2.2 Curve

A curve is a path that is not straight.

Examples: circle drawn by hand, snake’s movement, rainbow.

2.3 Open and Closed Figures

  • Open Figure: Does not end where it started. Example: letter "C."
  • Closed Figure: Starts and ends at the same point. Example: Circle, Square.

3. Plane Figures (2-D Shapes)

3.1 Triangle

A triangle has 3 sides, 3 corners, and 3 angles.

Examples: Traffic sign, sandwich piece.

3.2 Square

A square has 4 equal sides and 4 right angles.

Examples: Chessboard, window, dice face.

3.3 Rectangle

A rectangle has 4 sides and 4 right angles. Opposite sides are equal.

Examples: Blackboard, book, door.

3.4 Circle

A circle is a closed curve with no sides or corners. All points are at equal distance from the center.

Examples: Wheel, coin, plate.

3.5 Other Shapes

  • Oval (egg shape, balloon).
  • Polygon (triangle, square, pentagon, hexagon).

4. Solid Figures (3-D Shapes)

4.1 Cube

6 square faces, 12 edges, 8 corners.

Examples: Dice, Rubik’s cube, sugar cube.

4.2 Cuboid

6 rectangular faces, 12 edges, 8 corners.

Examples: Book, brick, cupboard.

4.3 Sphere

Round, no edges, no corners. All points equidistant from center.

Examples: Ball, globe, orange.

4.4 Cylinder

2 circular faces, 1 curved surface, no corners.

Examples: Bottle, glass, gas cylinder.

4.5 Cone

1 circular base, 1 apex (point), curved surface.

Examples: Ice-cream cone, party hat, traffic cone.

4.6 Pyramid

Polygon base, triangular faces meeting at apex.

Examples: Pyramids of Egypt, tent.

5. Corners, Edges, and Faces

  • Vertices (corners): Points where edges meet.
  • Edges: Line segments where two faces meet.
  • Faces: Flat surfaces of the solid.
Activity: Count faces, edges, and corners of a book, ball, and bottle.

6. Patterns and Symmetry

6.1 Patterns

Repeated arrangements of shapes, lines, or colors.

Examples: Rangoli, brick walls, clothes designs.

6.2 Symmetry

A figure is symmetrical if it can be folded into two equal halves.

Examples: Butterfly wings, square diagonals, letter "A."

7. Directions and Positions

Geometry also helps in understanding directions:

  • Left and Right
  • Top and Bottom
  • Inside and Outside
  • Near and Far
Classroom game: “Raise your right hand,” “Stand inside the circle.”

8. Real-Life Connections

  • Road signs (triangles, circles, rectangles).
  • Coins (circles).
  • Buildings (cuboids, cylinders).
  • Playgrounds (rectangular fields, circular tracks).

9. Classroom Activities

  • Shape Hunt in the classroom.
  • Make shapes with ice-cream sticks.
  • Origami folding.
  • Draw shapes using ruler/compass.
  • Sort solids into cubes, spheres, cylinders.

10. Word Problems

  1. A book has 4 sides. What shape is it? Rectangle
  2. Which shape has no corners? Circle
  3. A ball is an example of which solid? Sphere
  4. How many faces does a cube have? 6

11. Common Mistakes

  • Confusing square and rectangle.
  • Thinking circle has sides.
  • Forgetting that solids have faces, edges, corners.

12. Practice Exercises

Exercise 1: Identify Shapes

  1. Coin – ______
  2. Dice – ______
  3. Blackboard – ______
  4. Ball – ______

Exercise 2: Fill in the Blanks

  1. A square has ____ sides.
  2. A triangle has ____ corners.
  3. A circle has ____ sides.
  4. A cube has ____ faces.

Exercise 3: True or False

  1. A rectangle has 4 equal sides.
  2. A cone has 2 circular faces.
  3. A sphere has no edges.

Exercise 4: Match the Following

  • Cube → Dice
  • Sphere → Ball
  • Cylinder → Bottle
  • Cone → Ice-cream cone

13. Summary

  • Geometry studies shapes and figures.
  • Figures can be open or closed.
  • 2-D shapes: triangle, square, rectangle, circle.
  • 3-D shapes: cube, cuboid, sphere, cylinder, cone.
  • Shapes have sides, corners, faces, edges.
  • Geometry is useful in daily life.