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.
Grade 8, Mathematics — Number, Number Sense and Operations
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.