Lesson objective: Understand that two ratios can be scaled up or down in order to make a comparison.

Students bring prior knowledge of ratio concepts and language from 6.RP.A.1. This prior knowledge is extended to create proportions as students use multiplicative reasoning. A conceptual challenge students may encounter is understanding that both components of a ratio change in the same way in a proportional relationship.

The concept is developed through work with ratio tables, which helps students to clearly label the ratio components and multiply components accordingly.

This work helps students deepen their understanding of equivalence because in a proportion, each new ratio created is equivalent to the original ratio.

Students engage in Mathematical Practice 3 as they use their understanding of ratios to justify an argument for which camp offers the most pies for each camper.

Key vocabulary:

• ratio table
• proportion