In this lesson, students begin reasoning about the size of products when quantities are multiplied by one. They relate their previous work with equivalent fractions to interpreting multiplication by n/n as multiplication by 1. For example, 2/2 of 3/4 is 6/8, which is equivalent to 3/4. Then students rewrite fractions as decimals using equivalent fractions. For example, 1/5 = 2/10 = 0.2.