A bar tells you a count, if you read the scale
Two bars sit in two different graphs. Is the taller bar always more? Read each scale first. The scale says how much one square counts for.
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The rule
Not always. The same count is taller when each square counts less.
A bar graph shows a count as the length of a bar. Bars have the same width.
A gridline is one of the thin lines behind the bars.
The scale says how much one square or one gridline counts for. Read it first.
Bar length is the number of squares.
Bar length = count ÷ scale. Count = bar length × scale.
A rain gauge measures rain. Its readings are in millimetres, or mm.
Example
Cricket has 40 votes. One square is 5 votes. The bar is 40 ÷ 5 = 8 squares.
Make one square 10 votes. The same 40 votes need 40 ÷ 10 = 4 squares.
| Month | Rain (mm) |
|---|---|
| June | 40 |
| July | 70 |
| August | 55 |
| September | 25 |
July is 70 mm. At 10 mm per gridline, that is 70 ÷ 10 = 7 gridlines.
At 20 mm per gridline, it is 70 ÷ 20 = 3.5 gridlines.