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Ratio and Proportion

Chapter Synopsis

 

Understanding ratio, proportion and percent is a critical skill that is important when solving real-life problems. It is also a stepping stone to understanding more complicated mathematical concepts.

Three lesson plans are provided in this chapter. The first offers an introductory lesson about ratio and proportion. In the second plan, students use given data to compare families’ gasoline-powered vehicles to hybrid models. After calculating each vehicle’s unit rate of pounds of carbon expelled per gallon of gasoline, they find out which family leaves the greatest carbon footprint.

In the third plan, students use Google Earth to plan a two-week trip itinerary, taking in events at racetracks throughout Ohio. The challenge lies in developing the route that is the most efficient, given time and mileage constraints, to seven different racetrack locations. Students use the Google Earth measuring tool to calculate actual distances in miles and then use proportions to map the trip on an outline map of Ohio. This group of lessons can be used in the math classroom or as a cross-curricular unit with technology and social studies. The formative assessment can also be used as an introduction to learning about Google Earth and its features.

 

 

Standards Addressed

Grade 8, Mathematics — Number, Number Sense and Operations

08-10 Benchmark
G. Estimate, compute and solve problems involving real numbers, including ratio, proportion and percent, and explain solutions.

Y2003.CMA.S01.G08-10.BG.L08.I05 / Computation and Estimation

05.  Determine when an estimate is sufficient and when an exact answer is needed in problem situations, and evaluate estimates in relation to actual answers; e.g., very close, less than, greater than.

 

Y2003.CMA.S01.G08-10.BG.L08.I06 / Computation and Estimation

06. Estimate, compute and solve problems involving rational numbers, including ratio, proportion and percent, and judge the reasonableness of solutions.

 
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Formative Assessment: Solving Word Problems With Proportions (PDF file) Answers for Formative Assessment: Solving Word Problems with Proportions (PDF file) Ratio, Proportion and Percent (PDF file) Using Proportion to Solve Problems (PDF file) Automobile Carbon Footprint (PDF file) Driving Habits: The Guzzlers (PDF file) Driving Habits: The Middletons (PDF file) Driving Habits: The Greens (PDF file) Recording Sheet for Distances (PDF file) Google Map of Racecourses in Ohio (PDF file) Ohio: The Buckeye State (PDF file) Trip Itinerary (PDF file) Summative Assessment (PDF file) Summative Assessment Answers (PDF file) Chapter Synopsis Using Ratio and Proportion A Trail of Carbon Footprints On the Road Again! Ratio and Proportion Vocabulary