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Proportional Reasoning — Rates and Ratios

5 min readGrade 8 · Number

Proportional reasoning is one of the most broadly applicable tools in mathematics. Unit rates (km per litre, cost per item) and scale factors appear everywhere from recipe scaling to map reading. Students learn to set up and solve proportions, and to recognize when two quantities are — and aren't — in a proportional relationship.

What students explore

Proportional reasoning is one of the most broadly applicable tools in mathematics. Unit rates (km per litre, cost per item) and scale factors appear everywhere from recipe scaling to map reading. Students learn to set up and solve proportions, and to recognize when two quantities are — and aren't — in a proportional relationship.

Key ideas

Identify proportional relationships and distinguish them from non-proportional ones. Solve problems using unit rates. Use cross-multiplication and ratio tables to solve proportions. Apply proportional reasoning to scale, speed, and unit conversion.

Putting it together

Apply these ideas through worked examples, guided practice, and real-world problems.

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