1. 6-8 Misleading Graphs Warm Up Problem of the Day Lesson Presentation
Course 1
Warm Up
Problem of the Day
Lesson Presentation

2. Warm Up
Use the data below to answer each question.
1. What is the median?
2. What is the mode?
3. What is the range? 36
none 33

3. Problem of the Day
Nine students in a group found that their mean score was 86 for the first math test. On the next test, each student in the group scored 7 points higher than on the first test. What was their mean score for the two tests?
89.5

4. Learn to recognize misleading graphs.

5. Additional Example 1A: Misleading Bar Graphs
Why is this bar graph misleading?
Because the lower part of the vertical axis is missing, the differences in prices are exaggerated.

6. Additional Example 1B: Misleading Bar Graphs
What might people believe from the misleading graph? 1 2 __ 1 2 __
People might believe that Cars B and C cost 1 to 2
times as much as Car A. In reality, Cars B and C are only a few thousand dollars more than Car A.

7. Why is this bar graph misleading?
Check It Out: Example 1A
Money Raised
600
580
570
Dollars
560
550
540
530
4th graders 5th graders 6th graders
Why is this bar graph misleading?
The vertical axis begins at 530 rather than 0.

8. What might people believe from the misleading graph?
Check It Out: Example 1B
Money Raised
600
580
570
Dollars
560
550
540
530
4th graders 5th graders 6th graders
What might people believe from the misleading graph?
That the 5th graders have raised twice as much money as the 4th graders.

9. Additional Example 2A: Misleading Line Graphs
Why are these graphs misleading?
If you look at the scale for each graph, you will notice that the April graph goes from 54° to 66° and the May graph goes from 68° to 80°.

10. Additional Example 2B: Misleading Line Graphs
What might people believe from these misleading graphs?
People might believe that the temperatures in May were about the same as the temperatures in April. In reality, the temperatures in April were about 15 degrees lower.

11. Additional Example 2C: Misleading Line Graphs
Why is this line graph misleading?
The scale goes from $0 to $80, and then increases by $5.

12. Why are these graphs misleading?
Check It Out: Example 2A
November
September
Temperature (°F)
Temperature (°F)
Week
Week
Why are these graphs misleading?
If you look at the scale for each graph, you will notice that the September Graph goes from 85° to 70° and the November graph goes from 65° to 50°.

13. Check It Out: Example 2B November September Week Week
Temperature (°F)
Temperature (°F)
Week
Week
What might people believe from these misleading graphs?
People might believe that the temperatures in September were about the same as the temperatures in November. In reality, the temperatures in September were about 20 degrees higher.

14. Why is this line graph misleading?
Check It Out: Example 2C
Stock prices
Corp. C
Corp. D 80 70
Price of stock ($) 60 50
Year
Why is this line graph misleading?
The scale goes from $0 to $50, and then increases by $10.

15. Lesson Quiz
1. Why might this line graph be misleading?
2. What might people believe from the graph?
The scale does not start at zero.
Possible answer: that there were hardly any visitors on Monday