Data Through Pictures — Pictographs and Bar Graphs
When we collect information (like how many students like cricket, football, or chess), we have data. Showing data as pictures or bars makes it easy to read and compare. This chapter introduces pictographs and bar graphs.
Pictograph
A pictograph uses a picture or symbol to represent a set number of items. Each symbol stands for a fixed value (called a key).
For example: If smiley face = 5 students, then 3 smiley faces = 15 students.
- 1.Steps to read a pictograph:
- 2.Look at the key.
- 3.Count the symbols in each row.
- 4.Multiply: number of symbols x key value.
Bar Graph
A bar graph uses bars (rectangles) of different heights to show data. The height of each bar represents the value.
- The x-axis (horizontal) shows categories.
- The y-axis (vertical) shows the frequency or value.
- Read the value from the height of each bar.
Collecting and Organising Data
Data is often collected using a tally:
| | = 1, || = 2, ||| = 3, |||| = 4, and a diagonal cross through four = 5.
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In a pictograph, star = 10 books. A shelf has 4 stars. How many books?
4 x 10 = 40 books
A bar graph shows: Mango = 8, Apple = 5, Banana = 12. Which fruit is most popular?
Banana (bar height 12 is the tallest).
In a class of 30, 10 like chess, 12 like cricket, 8 like football. Draw tally marks for chess.
Ten marks: |||| |||| (two groups of 5).
A pictograph has a key of 1 symbol = 4 items. One row shows 3.5 symbols. How many items?
3.5 x 4 = 14 items (half a symbol = half the key value = 2).
A bar graph scale shows each small division = 2 students. A bar is 7 divisions tall. How many students?
7 x 2 = 14 students
Common mistakes
- Ignoring the key in a pictograph — always check what one symbol equals.
- Misreading the scale on a bar graph — count the divisions carefully.
Summary
Pictographs and bar graphs make data visual and easy to compare. Always read the key (pictograph) or scale (bar graph) first. Tally marks help collect and count data efficiently.