# Lesson 1

Decimal Numbers

### Lesson Purpose

### Lesson Narrative

In previous units, students reasoned about the size of fractions, compared them, and wrote equivalent fractions. They performed some operations: multiplying fractions by whole numbers, and adding and subtracting fractions with the same denominator including fractions with denominators of 10 and 100. Students also used their understanding of equivalent fractions to add tenths and hundredths.

In this lesson, students rely on their knowledge of fractions to express tenths and hundredths as **decimals**. They begin to see connections between fraction notation, the names of fractions in words, and decimal notation. They also start to notice the structure of the decimal notation and how it relates to place value. Students use increasingly precise language to read decimals through this section (MP6). Students will develop this new understanding over several lessons, so they are not expected to name the value of each place of a decimal at this time.

- Representation

- MLR2

### Learning Goals

Teacher Facing

- Make sense of tenths and hundredths in decimal notation using unit square grids.

### Student Facing

- Let’s learn about decimals.

### Required Materials

Materials to Gather

### Required Preparation

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 20 min |

Activity 2 | 15 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

### Suggested Centers

- Rolling for Fractions (3–5), Stage 1: Equivalent Fractions (Supporting)
- Get Your Numbers in Order (1–5), Stage 4: Denominators 2, 3, 4, 5, 6, 8, 10, 12, or 100 (Supporting)