Measurement & Data
Scaled Bar Graphs
Drawing and interpreting a scaled bar graph.
Graphs Where Each Bar Represents More Than One
In earlier grades, a bar graph's bars each represented a count of exactly 1. A scaled bar graph is more powerful — each unit of a bar's length can represent any fixed amount, like 2, 5, or 10, letting a graph display much larger numbers in a compact space.
Definition — Scale
To read a scaled bar graph, first check the scale in the key. Then, for any bar, count how many units long it is and multiply by the scale to find the actual value it represents.
Worked Example — Reading a Scaled Bar Graph
Worked Example — Comparing Two Bars on a Scaled Graph
| Sport | Bar length (units) | Students |
|---|---|---|
| Soccer | 6 | 30 |
| Basketball | 4 | 20 |
| Tennis | 2 | 10 |
Tip
Common Mistakes
Reading the number of units a bar reaches as the final answer, forgetting to multiply by the scale.
The bar length alone isn't the answer on a scaled graph — always multiply the number of units by the scale shown in the key.
Using a different scale than the one shown in the graph's key, especially when comparing to a previously seen graph with a different scale.
Always check the specific key for the graph being read — the scale can be different from one graph to the next.
Key Takeaways
- A scaled bar graph's key shows how many items each unit of bar length represents.
- Finding a bar's value means multiplying its length in units by the scale.
- Different scaled graphs can use different scales, so the key must always be checked.
Summary
Scaled bar graphs use multiplication to represent large amounts of data compactly. The next lesson introduces a different way to display data — line plots — often used with the fraction measurements from earlier in this grade.
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