Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

Solutions for Session 4, Part A

See solutions for Problems: A1 | A2 | A3 | A4 | A5

 Problem A1 Either answer is defendable. The first class has a higher percentage of girls -- half its students are girls -- while girls make up less than half of the second class. The second class, however, has a larger number of girls. Essentially, the meaning of "more" is the real issue in this problem.

 Problem A2 An absolute comparison is done by counting: 22 is more than 20, because you count to 20 before counting to 22. Or it can be done by subtraction: 22 is more than 20 because 22 - 20 = 2, a positive number.

 Problem A3 A relative comparison is done by finding percentages or fractions or by finding a rate. On a quiz, 22 out of 25 is worse than 18 out of 20, even though 22 is larger in absolute terms.

 Problem A4 You might use absolute comparisons when looking at annual salaries, but a relative comparison when looking at per-hour wages. An absolute comparison might tell you that extended cable TV is more expensive than basic cable, but a relative comparison might tell you that you get more channels per dollar on extended cable. A truck may be able to travel further than a compact car before needing to be refueled (an absolute comparison), but the compact car may travel more miles per gallon (a relative comparison).

 Problem A5 This is a relative comparison, because it compares heights "per student" by using the average. An absolute comparison might compare the total height of all eighth graders to the total height of all seventh graders.

 Session 4: Index | Notes | Solutions | Video