Statistics
Grade 1-2Bar Charts & Pictograms
Bar charts and pictograms are two of the simplest ways to display data, and exam questions test whether you can read values accurately, combine or compare them, and work with a pictogram key, including half symbols. This lesson covers reading values from a bar chart, finding totals and differences, reading a pictogram key, and working out how many symbols to draw for a given amount.
Written by Asad, Co-Founder of Teachably
Video walkthrough coming soon
The written lesson below covers everything you need in the meantime.
Reading values from a bar chart
Find the category on the horizontal axis, trace the top of its bar across to the vertical axis, and read off the value using the scale.
On a bar chart showing favourite fruit, the bar for Orange reaches up to 10 on the vertical axis, so 10 students chose Orange.
Finding totals and differences
To find a total, read off and add together the value for every category. To find a difference, read off the two values needed and subtract the smaller from the larger.
If Apple = 8, Banana = 5, Orange = 10 and Grape = 3, the total surveyed is 8 + 5 + 10 + 3 = 26, and 8 − 3 = 5 more students chose Apple than Grape.
Reading a pictogram key
A pictogram key shows what one full symbol represents. A half symbol represents half of that value, so multiply the number of symbols, including any half symbols, by the value of one symbol.
If each symbol represents 10 mm of rainfall, and Tuesday shows two and a half symbols, then the rainfall on Tuesday is 2.5 × 10 = 25 mm.
Working out how many symbols to draw
Divide the amount to be shown by the value of one symbol, then round the result to the nearest half symbol, since pictograms only use whole and half symbols.
If each symbol represents 10 pounds, and David saved £35, then 35 ÷ 10 = 3.5, so 3 full symbols and 1 half symbol should be drawn.
Worked Examples
Three exam-style questions, fully solved.
The bar chart shows the favourite fruit of a group of students. How many students chose Orange as their favourite fruit?
Easy- 1.Find the Orange bar and trace it up to the vertical axis: the bar reaches 10
Answer: 10 students
In a pictogram, each symbol represents 10 pounds. David saved £35. How many symbols (including any half symbols) should be drawn to represent this?
Medium- 1.Divide the amount by the value of one symbol: 35 ÷ 10 = 3.5
- 2.Round to the nearest half symbol: 3.5 symbols
Answer: 3 full symbols and 1 half symbol
The pictogram shows the rainfall recorded over three days, where each symbol represents 10 mm. How much more rainfall was recorded on Monday than Wednesday, if Monday shows 4 symbols and Wednesday shows 1 symbol?
Hard- 1.Find the rainfall for Monday: 4 × 10 = 40 mm
- 2.Find the rainfall for Wednesday: 1 × 10 = 10 mm
- 3.Subtract to find the difference: 40 − 10
Answer: 30 mm
Avoid These
The most common mistakes students make.
Misreading the scale on a bar chart's vertical axis, especially when the gridlines increase in steps other than 1, such as steps of 3 or 4.
Forgetting that a half symbol in a pictogram represents exactly half of the stated value, not always exactly one extra unit.
When finding a total from a bar chart or pictogram, missing out one of the categories or misreading one of the bars or symbol counts.
When working out how many symbols to draw, rounding to the nearest whole symbol instead of the nearest half symbol.
Multiplying the number of symbols by the wrong value, for example using the number of categories instead of the value stated in the key.
FAQ
Questions parents and students ask.
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What to learn next
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