Graphs | Year 3 Mathematics IGCSE (Cambridge) - Class 3 PDF Download

Introduction:

In this chapter, we will learn how to represent data using different types of graphs. Graphs are a great way to show information in a visual way, making it easier to understand. By the end of this chapter, you will be able to create bar charts, picture graphs, and interpret the data shown in these graphs.

1. What are Graphs?

• Definition of Graphs:

  A graph is a way of representing data using pictures, lines, or bars. Graphs help us understand information quickly by showing data visually. For example, a graph can show how many people like different fruits or how much it rained in a month.

• Why Do We Use Graphs?

  We use graphs to make it easier to compare and analyze data. Instead of looking at a list of numbers, we can see patterns and trends in a graph, which helps us make decisions or draw conclusions.

2. Types of Graphs

• Bar Chart:

  A bar chart uses bars of different lengths to represent data. The longer the bar, the larger the value it represents. Bar charts are used to compare different categories. Each bar represents one category, and the height of the bar shows the value of that category.

  Example: If we want to show how many students like different sports, we could use a bar chart where each bar represents a sport, and the height of the bar shows how many students like it.

• Picture Graph:

  A picture graph uses pictures or symbols to represent data. Each picture or symbol stands for a specific number of items. For example, one picture of an apple could represent 2 students who like apples.

  Picture graphs are helpful for showing data in a fun and easy-to-understand way. The pictures make it easier for younger children to grasp the idea of data representation.

• Line Graph:

  A line graph shows data points connected by a line. Line graphs are used to track changes over time. For example, we can use a line graph to show how the temperature changes throughout the day or how the number of books read increases over a month.

3. Creating a Bar Chart

Steps to Create a Bar Chart:

Follow these steps to create a bar chart:

• Step 1: Collect the data you want to display.
• Step 2: Choose the categories you want to compare. For example, types of fruit (apples, bananas, oranges).
• Step 3: Draw a vertical axis (for values) and a horizontal axis (for categories).
• Step 4: Label the axes with the correct categories and numbers.
• Step 5: Draw bars for each category, making the height of each bar correspond to the value of that category.
• Example: If 5 students like apples, 8 students like bananas, and 4 students like oranges, the bar chart would look like this:    4. Creating a Picture Graph

Steps to Create a Picture Graph:

Follow these steps to create a picture graph:

• Step 1: Collect the data you want to represent.
• Step 2: Decide what picture or symbol will represent each unit of data.
• Step 3: Draw a column of pictures for each category, where each picture represents a certain number of items.
• Step 4: Label the pictures and the categories to make it easy to understand.
• Example: If 4 students like apples, 6 students like bananas, and 3 students like oranges, you could use apples, bananas, and oranges as symbols for the graph:

  Each fruit represents 1 student.

5. Reading and Interpreting Data from Graphs

• How to Read Data:

  To read data from a graph, look at the labels and the scale. The labels tell you what each bar, picture, or line represents, and the scale tells you how much each unit is worth.

• Example:

  If a bar chart shows the number of books read by students, and each bar represents 2 books, you can count how many units the bar reaches to find out how many books were read. If the bar reaches 3 units, the student read 6 books.

• Making Conclusions from Graphs:

  Once you read the graph, you can make conclusions. For example, you can say, "Bananas are the most popular fruit because the banana bar is the tallest," or "The student who likes apples has read fewer books than the student who likes bananas."

6. Practice Questions:

• Create a bar chart for the following data:
  Apples - 5 students
  Bananas - 8 students
  Oranges - 4 students
• Draw a picture graph to show how many students like apples, bananas, and oranges. Each picture should represent 1 student.
• Read the bar chart showing the number of students in different sports teams, and answer the following questions: Which sport has the most players? Which sport has the fewest players?
• What type of graph would be best to show the number of students who like different ice cream flavors in your class?