Numbers and Their Operations — Applications of Ratio and Proportion

About this lesson

This unit focuses on applications of ratio and proportion in real-life contexts. It begins with scale drawings, explaining the concept as the ratio of a dimension in a drawing or model to the real dimension. Students learn to calculate real lengths from scale drawings, distinguish between magnification (scale >1) and minimization (scale <1), and use double number lines as a strategy. The unit then covers proportional division, where an amount is divided into parts according to a given ratio, with examples involving profits and investments. Finally, it addresses percentage applications, specifically calculating discounts (deductions) and increases (taxes or profits), including finding the price after a discount, the original price before a discount, and the total cost after adding a tax. Throughout, real-world contexts such as maps, building models, business profits, and shopping are used. By the end, students should be able to solve problems involving scale drawings, proportional division, and percentage-based price changes.