Idea 7of 22Builds onThe shares make one whole
Compare shares, not counts
How do you compare two groups of different sizes?
Today you'll discover
- why a bigger count can be a smaller share
- how to compare two shares
- when different counts are the same share
Think firstRoom 12 has 20 students, Room 14 has 25
Which room has the bigger share of walkers?
Decide first, then press Next. Look at the size of each group, not only the counts.
Two tables side by side: Room 12 with 20 students (walk 8, bus 6, car 4, bike 2) and Room 14 with 25 (walk 9, bus 6, car 5, bike 5), the walk row ringed. Then each count over its total, then as decimals: walk 0.40 and 0.36, and the car row, 0.20 in both. The last step shows Grade 4 and Grade 5 at recess, with 10 tag players each.
See the whole ideathe big idea and the key word, in one place
The big idea
To compare groups of different sizes, compare their shares, not their counts.
Compare themCounts: Room 14 has more walkers, 9 against 8. Shares: Room 12 walks more, 0.40 against 0.36. Only the shares are fair here.
Easy to get wrongEqual counts are not equal shares when the groups differ. 10 of 20 is half; 10 of 25 is less.
Key word
- share
- a part of the whole group, written as a fraction or decimal; another word for relative frequency
Ready to use it?
- Compare two groups of different sizes by their shares.
- Spot when a count comparison misleads.