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Mathematics Class 8 - Introduction To-Graphs Notes

Comprehensive study notes for Class 8 - Introduction To-Graphs olympiad preparation

Introduction to Graphs

Welcome to the chapter on Introduction to Graphs for Class 8. In this chapter, you will learn what graphs are, how to read and draw different types of graphs, and how graphs help us show information clearly. By the end of this chapter, you will be able to use graphs to solve problems and present data!

Introduction

Graphs are pictures that show information in a simple way. They help us understand numbers and data quickly. We use graphs in math, science, and everyday life.

Types of Graphs

  • Bar Graph: Uses bars to show numbers and compare things.
  • Line Graph: Uses lines to show changes over time.
  • Pictograph: Uses pictures or symbols to show data.
  • Pie Chart: Shows data as parts of a circle.

Parts of a Graph

  • Title: Tells what the graph is about.
  • Axis: The lines that show the sides of the graph (X-axis and Y-axis).
  • Scale: Shows the value of each mark on the axis.
  • Labels: Tell what each axis and bar/line/picture means.

Reading a Graph

  • Look at the title to know what the graph shows.
  • Check the labels and scale on the axes.
  • See how high or long each bar, line, or picture is.
  • Compare the data shown.

Drawing a Bar Graph

To draw a bar graph:

  • Draw two axes (X and Y).
  • Label the axes and give a title.
  • Choose a scale for the Y-axis.
  • Draw bars for each item according to the data.

Uses of Graphs

  • Show marks scored in exams.
  • Compare sales in shops.
  • Show temperature changes over days.
  • Present survey results.

Fun Activity: Make Your Own Graph!

Collect data about your classmates’ favorite fruits. Draw a bar graph to show the results!

Summary

  • Graphs help us show and understand data easily.
  • There are different types of graphs: bar, line, pictograph, and pie chart.
  • We use graphs in many subjects and in daily life.

Practice Questions

  1. What is a bar graph?
  2. Name two types of graphs.
  3. What does the title of a graph tell us?
  4. How do you read the scale on a graph?
  5. Draw a simple bar graph using this data: Apples – 5, Bananas – 7, Oranges – 3.

Challenge Yourself

  • Collect data about your family’s favorite colors and show it in a pictograph.
  • Explain how a line graph is different from a bar graph.

Did You Know?

  • Florence Nightingale used graphs to show how to save lives in hospitals!
  • Graphs are used in newspapers, TV, and the internet to show information.

Glossary

  • Graph: A picture that shows data.
  • Axis: The lines on the sides of a graph (X and Y).
  • Scale: The value of each mark on the axis.
  • Bar: A block that shows a number in a bar graph.

Answers to Practice Questions

  1. A bar graph uses bars to show and compare numbers.
  2. Line graph, pictograph (any two types).
  3. It tells what the graph is about.
  4. By looking at the numbers marked on the axis.
  5. Draw three bars: Apples (5), Bananas (7), Oranges (3).

Practice drawing and reading graphs to become a data expert!

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