Idea 4of 22Builds onA scale counts in equal steps
Pick a scale that fits the data
How do you choose what a scale counts by?
Today you'll discover
- what goes wrong with too small a step
- what goes wrong with too big a step
- a quick way to find a step
Think first10 grid lines, counting by 1s
The biggest amount is 48 cans. What goes wrong when the scale counts by 1s?
Decide first, then press Next. Compare the biggest value with the top of the scale.
The same four cans bars on a grid of 10 lines three ways. Counting by 1s, every bar runs off the top of the grid. Counting by 100s, every bar is a sliver near the bottom. Counting by 5s, the scale reaches 50 and the tallest bar, 48, fits just under the top. The last step shows Bike-a-thon bars with the scale numbers hidden.
See the whole ideathe big idea and the key word, in one place
The big idea
Choose a scale so the biggest value fits and every bar is easy to read.
Find a stepBiggest value ÷ number of lines, then round up to a friendly step: 1, 2, 5, 10, 20, 25, 50 or 100.
Easy to get wrongA step that is too big squashes the bars; a step that is too small makes them run off the grid.
Key word
- appropriate scale
- a scale whose step lets the biggest value fit and keeps the bars easy to read
Ready to use it?
- Choose a step for a graph's scale.
- Say why a scale does or does not fit.