Idea 15of 22Builds onRatios on a double number line
A rate compares different units
What makes a rate different from other ratios?
Today you'll discover
- what the units of a rate are
- rates in everyday life
- how a rate scales like a ratio
Think firstA train goes 240 km in 3 hours
Which of these is a rate?
Decide first, then press Next. Read the name of each line.
Two number lines, hours on top and kilometres below. First 3 hours lines up with 240 km; then 6 hours with 480 km, with arcs marked plus 3 and plus 240. Then a heart's line, 18 beats every 15 seconds, and a printer's, 30 pages every 2 minutes. The last step shows a cyclist, 45 km in 3 hours.
See the whole ideathe big idea and the key word, in one place
The big idea
A rate is a ratio that compares two amounts with different units, like km and hours.
Rates240 km in 3 hours. 18 heartbeats in 15 seconds. 30 pages in 2 minutes. Each pairs two different units.
Same toolsA rate scales like any ratio: multiply or divide both amounts by the same number. A double number line works for both.
Key word
- rate
- a ratio that compares two amounts measured in different units, like kilometres and hours
Ready to use it?
- Tell a rate from a ratio by its units.
- Scale a rate up on a double number line.