Lesson 1

Números decimales

Lesson Purpose

The purpose of this lesson is for students to make sense of tenths and hundredths in decimal notation.

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

  • Aprendamos sobre los decimales.

Required Materials

Materials to Gather

Required Preparation

CCSS Standards


Building Towards

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

How readily did students make connections between the fraction notation and decimal notation of tenths and hundredths? How did the use of square grids support the range of learners in making connections?

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)

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Teacher Presentation Materials pdf docx