Proportional Reasoning — Percents, Rates, and Scale
Proportional reasoning deepens in Grade 9. Students tackle multi-step percent problems (a 15% salary increase followed by a 10% decrease), scale factor problems (similar triangles, map distances), and financial applications (simple interest, exchange rates). Each context strengthens the underlying multiplicative relationship.
What students explore
Proportional reasoning deepens in Grade 9. Students tackle multi-step percent problems (a 15% salary increase followed by a 10% decrease), scale factor problems (similar triangles, map distances), and financial applications (simple interest, exchange rates). Each context strengthens the underlying multiplicative relationship.
Key ideas
Solve multi-step percent problems: percent change, original value, final value. Solve problems involving rates, unit rates, and unit conversion. Apply scale factors to diagrams, maps, and similar figures. Use proportional reasoning to solve real-world financial problems.
Putting it together
Apply these ideas through worked examples, guided practice, and real-world problems.