Lesson 8 of 11
Two honest pictures, one truth
Show on a big screenA bus had 48, 50 and 52 seats filled on three Mondays. The same three numbers can be drawn two ways. The side scale is the row of numbers up the side.
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Step 1 of 2
- Scale from 0 to 56: the rise looks small.
- Scale from 44 to 56: the same rise looks big.
The side scale is a choice
The rise from 48 to 52 is 4 seats.
On a 0 to 56 scale, the rise is 4 of 56. That is 4 ÷ 56, one fourteenth. On a 44 to 56 scale, the height is 56 − 44 = 12. The rise is 4 of 12. That is 4 ÷ 12, one third.
On the short scale, each seat takes more height. So the same rise looks bigger.
Neither chart has a wrong number. The picture changes, and the seat counts do not.
Rule: A line graph may start above zero. Say where it starts.
Try the lab to finish this lesson.