Lesson 20

The purpose of this lesson is for students to solve fraction division problems that ask: “How many in one group?”

In this optional lesson, students solve problems where a whole number quantity is a unit fraction of an unknown whole number.  In these situations students may rely on their understanding of the relationship between multiplication and division. For example, if 8 ounces is $\frac{1}{4}$ of the amount of water in a bottle, students might represent this with a tape diagram:

The tape diagram suggests the equation $8 = \frac{1}{4} \times {?}$ which students will likely solve by seeing that ${?} = 4 \times 8$. The equation $8 = \frac{1}{4} \times {?}$ can also be written using division with the equation ${?} \div 4 = 8$.

What do you love most about math? How are you sharing that joy with your students and encouraging them to think about what they love about math?