# Lesson 20

How Much in the Group? (optional)

### Lesson Purpose

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

### Lesson Narrative

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 \({?} \div 4 = 8\).

- Engagement

- MLR8

### Learning Goals

Teacher Facing

- Represent and solve problems involving division of a whole number by a unit fraction.

### Student Facing

- Let’s solve more problems involving multiplication and division with fractions.

### Required Preparation

### CCSS Standards

Addressing

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 20 min |

Activity 2 | 10 min |

Activity 3 | 10 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

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?

### Suggested Centers

- How Close? (1–5), Stage 6: Multiply to 3,000 (Addressing)
- Rolling for Fractions (3–5), Stage 5: Divide Unit Fractions and Whole Numbers (Addressing)