Content Area: Math

 

Index: 4.1C Grade 8 CPI 2

 

Standard: 4.1 - Number and Numerical Operations

 

Strand: C - Estimation

 

Cumulative Progress Indicator: 2 -   The student will use equivalent representations of numbers such as fractions, decimals, and percents to facilitate estimation.

 

Grade: 8

 

Sample Activities:

 

·        Students judge the reasonableness of the results of fraction addition and subtraction by "rounding off" the fractions involved to 0, 1/2, or 1.

 

·        Students use fractions, decimals, or mixed numbers interchangeably when one form of the number makes estimation easier than another. For example, rather than estimating 33 1/3% of $120, students consider 1/3 x 120 which yields a much quicker estimate.

 

·        Similarly, in their work with percents, students master the common fraction equivalents for familiar percentages and use fractions for estimation in appropriate situations. For example, an estimate of 117% of 50 can most easily be obtained by considering 6/5 of 50.

 

·        Students collect and bring to class sales circulars from local papers which express the discounts on sale items in a variety of ways including percent off, fraction off, and dollar amount off. For items chosen from the circular, the students discuss which form is the easiest form of expression of the discount, which is most understandable to the consumer, and which makes the sale seem the biggest bargain.