A graph is a story told with dots and lines. Reading one well means knowing what each axis measures before you look at the shape.
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Choosing the wrong kind of graph is a favourite exam question. Each one answers a different question.
📊 Match the graph to the job
| Graph | Best for | Example |
|---|---|---|
| Bar graph | comparing separate things | marks of five students |
| Pie chart | showing parts of one whole | how a day is spent |
| Line graph | showing change over time | temperature through the day |
| Histogram | grouped data, bars touching | heights in ranges |
| Pictograph | simple counts with symbols | books read each month |
Bar graph or histogram? A bar graph has gaps between the bars because the categories are separate. A histogram has no gaps, because the data is grouped into continuous ranges.
A whole circle is 360° and also 100%. Every pie-chart question moves between those two.
🥧 Converting
| To find | Do this |
|---|---|
| Angle from a percentage | percentage ÷ 100 × 360 |
| Angle from a fraction | fraction × 360 |
| Percentage from an angle | angle ÷ 360 × 100 |
| Quantity from an angle | angle ÷ 360 × total |
Useful landmarks: a quarter is 90°, a half is 180°, a third is 120°, and 10% is 36°. Spotting one of these saves the calculation entirely.
Two number lines crossing at right angles let you name any point with a pair of numbers.
Order matters: (x, y). The first number is along the x-axis (across), the second is up the y-axis. The point (3, 5) is not the same as (5, 3). "Along the corridor, then up the stairs."
🗺️ The four quadrants
| Quadrant | x | y | Example |
|---|---|---|---|
| I | + | + | (3, 5) |
| II | − | + | (−3, 5) |
| III | − | − | (−3, −5) |
| IV | + | − | (3, −5) |
The origin is (0, 0). A point on the x-axis has y = 0, like (4, 0). A point on the y-axis has x = 0, like (0, 7).
12 questions on graphs and coordinates. Read the axes first. 🍀
