Graphs
Pictograms and bar charts
Pictograms and bar charts are two ways to show data so you can compare it quickly. A pictogram uses pictures; a bar chart uses bars. Always read the key or the number scale first.
Reading a bar chart
A bar chart uses bars to compare data. It has two axes — one going up and one going across. For upright bars, follow the top of each bar across to the number scale to read how many. The taller the bar, the bigger the amount.
Reading a pictogram
A pictogram uses pictures instead of bars, like a visual tally. The key tells you what one picture stands for. If a picture stands for 1, count the pictures. If a picture stands for 2 (or 5), multiply: 4 pictures × 2 = 8.
Comparing and calculating
Once you can read the data you can compare it: find the biggest and smallest, work out 'how many more', or add amounts together for a total. Example: 9 guinea pigs and 1 turtle → 9 − 1 = 8 more guinea pigs.
Worked examples
Reading a bar chart
- You want to know how many cats a pet shop has.
- Find the bar labelled 'cat'.
- Follow the top of the bar across to the number scale.
Answer: The cat bar reaches 8, so there are 8 cats.
Reading a pictogram with a key
- The key says each picture stands for 2 books.
- Ben has 4 book pictures.
- Multiply: 4 × 2.
Answer: Ben read 8 books.
Comparing two amounts
- A shop has 9 guinea pigs and 1 turtle.
- To find how many more guinea pigs, subtract.
- 9 − 1.
Answer: There are 8 more guinea pigs than turtles.
Where you see this in real life
- Showing how many hours of rain fell on each day of the week.
- Comparing how many of each pet a shop has.
- Recording how many books each friend read this week.
Key words
- Pictogram
- A chart that uses pictures to show and compare data.
- Bar chart
- A chart that uses bars to compare data, with two axes.
- Key
- A note on a pictogram telling you what one picture stands for.
- Axis
- A line on a chart — one goes up (vertical) and one goes across (horizontal). Two of them are axes.
- Data
- Information you collect, such as numbers or amounts.