Maths

Data Handling

Class 3

🎯 Learning Objectives

πŸ“– What is Data?

Data means information that we collect. When we ask questions and write down the answers, we are collecting data!

For example, if you ask all your classmates "What is your favourite fruit?" and write down their answers β€” that collection of answers is called data.

But a long list of answers is hard to understand. So we organise data using tally charts, pictographs, and bar graphs to make it easy to read.

Tally Marks

Tally marks are a quick way to count things. We draw one line for each item. After every 4 lines, the 5th line goes across them (like a gate). This makes counting in groups of 5 easy.

NumberTally MarksNumberTally Marks
1|6|||| |
2||7|||| ||
3|||8|||| |||
4||||9|||| ||||
5||||10|||| ||||
Think about it: Why do we cross the 5th line? Because it makes counting faster! Instead of counting one by one, we count in groups of 5.
Tally marks from 1 to 10 showing how to draw and count tallies

Tally Chart (Frequency Table)

A tally chart organises data into a table with tally marks and totals.

Example: Favourite Fruits of Class 3B (30 students)

Arjun asked his classmates about their favourite fruit. Here is the tally chart:

FruitTally MarksNumber of Students
Mango πŸ₯­|||| |||8
Banana 🍌|||| |6
Apple 🍎|||| ||||10
Grapes πŸ‡||||4
Orange 🍊||2

Questions we can answer from this chart:

  • Which fruit is most popular? β†’ Apple (10 students)
  • Which fruit is least popular? β†’ Orange (2 students)
  • How many more students like Mango than Grapes? β†’ 8 βˆ’ 4 = 4 more
  • Total students surveyed? β†’ 8 + 6 + 10 + 4 + 2 = 30

Pictograph

A pictograph uses pictures or symbols to show data. Each picture stands for a certain number of items.

Example: Books Read by Students in One Month

Key: Each πŸ“š = 2 books

StudentBooks (πŸ“š = 2 books)Total
SitaπŸ“šπŸ“šπŸ“š6
RaviπŸ“šπŸ“šπŸ“šπŸ“š8
MeenaπŸ“šπŸ“š4
ArjunπŸ“šπŸ“šπŸ“šπŸ“šπŸ“š10

Reading the pictograph:

  • Who read the most books? β†’ Arjun (10 books)
  • How many books did Sita read? β†’ 3 pictures Γ— 2 = 6 books
  • How many more books did Ravi read than Meena? β†’ 8 βˆ’ 4 = 4 more
Pictograph showing favourite sports β€” cricket, football, badminton and kabaddi

Bar Graph

A bar graph uses bars (rectangles) to show data. The taller the bar, the bigger the number. Bar graphs are easy to compare because you can see which bar is tallest at a glance.

Parts of a bar graph:

Example: Favourite Colours of Class 3A
ColourNumber of Students
Red7
Blue9
Green5
Yellow4
Pink6

In a bar graph, Blue would have the tallest bar (9) and Yellow the shortest (4).

Bar graph showing favourite colours with coloured bars

How to Draw a Bar Graph

Follow these steps:

  1. Step 1: Draw two lines β€” one horizontal (X-axis) and one vertical (Y-axis).
  2. Step 2: Write the categories on the X-axis (e.g., Red, Blue, Green...).
  3. Step 3: Write numbers on the Y-axis (0, 1, 2, 3... up to the highest value).
  4. Step 4: Draw bars for each category. The height of each bar = the number.
  5. Step 5: Give your graph a title.
Remember: All bars should have the same width. Leave equal gaps between bars. Always start the Y-axis from 0.

πŸ“ Key Words

WordMeaning
DataInformation collected by asking questions or observing
Tally MarksLines used to count items in groups of 5
Tally ChartA table showing data using tally marks
PictographA chart using pictures to represent data
Bar GraphA chart using bars (rectangles) to show data
KeyTells what each picture stands for in a pictograph
X-axisThe horizontal line in a graph (categories)
Y-axisThe vertical line in a graph (numbers)
⭐ Key Points to Remember

Finished learning? Now test what you know!