Knowledge Organiser: Bar Charts and Pictograms
Part of Bar Charts & Pictograms · GCSE GCSE Mathematics revision
This topic summary covers Knowledge Organiser: Bar Charts and Pictograms within Bar Charts & Pictograms for GCSE Mathematics. Revise Bar Charts & Pictograms in Statistics for GCSE Mathematics with 11 exam-style questions and 20 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 11 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 11 of 11
Practice
11 questions
Recall
20 flashcards
Knowledge Organiser: Bar Charts and Pictograms
Key Terms
- Bar chart: A chart using equal-width bars to compare categories
- Pictogram: A chart using symbols where each symbol represents a set number
- Key: States what each symbol in a pictogram represents
- Compound bar chart: Bars split to compare two or more groups side by side
- Discrete data: Separate categories (the data type bar charts represent)
- Frequency: The count for each category, shown on the vertical axis
Must-Know Facts
- All bars must be the same width with equal gaps between them
- The y-axis must start at zero — truncating it misleads the reader
- Every chart needs a title, axis labels, and a scale
- Pictogram symbols must all be identical in size
- Partial symbols (halves, quarters) must be drawn accurately, not estimated
- Bar charts are for discrete/categorical data — not continuous data
- A pictogram always requires a key showing the value of each symbol
Key Methods
- Reading pictogram: count symbols × value shown in key
- Drawing pictogram: value ÷ key value = number of symbols needed
- Reading bar chart: trace bar top horizontally to y-axis scale
- Choose y-axis scale so the tallest bar fills most of the available space
Common Mistakes
- Misreading the pictogram key: Each symbol represents the key value — if the key says 1 symbol = 4 people and there are 2.5 symbols, the frequency is 10, not 2.5
- Bars touching in a bar chart: Bars in a bar chart for categorical data should have gaps between them — touching bars indicate continuous data (histogram)
- Not labelling axes: Both axes must be labelled with a title and units — an unlabelled y-axis loses a mark even if the bars are correct
- Unequal bar widths: All bars in a bar chart must have equal widths — only histograms can have variable-width bars
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Practice Questions for Bar Charts & Pictograms
In a pictogram, the key shows that one symbol represents 4 people. A row shows 3 and a half symbols. How many people does this row represent?
A bar chart comparing two companies' sales has a vertical axis starting at 900 rather than 0. Company A has sales of 950 and Company B has sales of 1000. Explain why this bar chart could be misleading.
Quick Recall Flashcards
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