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Content Area: Math
Index: 4.1B Grade 8 CPI 4
Standard: 4.1 - Number and Numerical Operations
Strand: B - Numerical Operations
Cumulative Progress Indicator: 4 - The student will solve problems involving proportions and percents.
Grade: 8
Sample Activities:
· Students use The Geometer's Sketchpad software to draw a geometric figure on a computer screen, scale it larger or smaller, and then compare the lengths of the sides of the original with those of the scaled image. They also compare the areas of the two.
· Students are comfortable using a variety of approaches to the solution of proportion problems. Example: If 8 pencils cost 40 cents, how much do 10 pencils cost? This problem can be solved by: unit-rate method 8 pencils for 40 cents means 5 cents per pencil or 10 x 5=50 cents for 10; factor-of-change method 10 pencils is 10/8 of 8 pencils, so cost is (10/8)x40=50 cents; cross multiplication method 8/40 = 10/x, 8x = 400, so x=50 cents.
· Students set up a part/whole proportion as one method of solving percent problems.
· Students spend $100 by selecting items from a catalog. They must compute sales tax and consider it in deciding what they will buy.
Sample Assessment Question:
· A newspaper reported that one weekend the movie Batman Returns earned $14.8 million. According to that newspaper, the figure represented 42% of the previous weekend's earnings. Approximately how much did Batman Returns earn during the previous weekend? o a) 25,500,000 o b) 35,200,000 o c) 255, 000,000 o d) 352,000,000
The correct answer is B.
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