Lesson objective: Understand that percents are a way to compare relationships that are not based on the same reference whole by standardizing the comparison to a reference whole of 100.

Students bring prior knowledge that a percent is a type of ratio where a part is linked to a whole represented by a value of 100 from 6.RP.A.3.C This prior knowledge is extended to comparing relationships between values based on different totals as students calculate percents and use them to make comparisons. A conceptual challenge students may encounter is that percents represent the same value as the original relationship or ratio.

The concept is developed through work with double number lines, which provides a visual model relationships between the various values.

This work helps students deepen their understanding of equivalence because students experience that a relationship written as a percent is equivalent to the original relationship.

Students engage in Mathematical Practice 1 as they make sense of and persevere in solving problems while applying their understanding of proportional reasoning to percents.

**Key vocabulary:**

- double number line
- equivalent
- fraction
- percent
- ratio