Lesson 3

Doubles and Halves

Est. Class Sessions: 2
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Mathematical Standards

1.OA.A
Represent and solve problems involving addition and subtraction. (1.OA.A.1, 1.OA.A.2)
1.OA.B
Understand and apply properties of operations and the relationship between addition and subtraction. (1.OA.B.3)
1.OA.C
Add and subtract within 20. (1.OA.C.6)

Standards for Mathematical Practice

MP1.
Make sense of problems and
persevere in solving them.
MP2.
Reason quantitatively.
MP4.
Model with mathematics.
MP7.
Look for and make use of structure.

Students extend work from Lesson 2 Seeing Doubles by exploring the relationship between doubling and halving a number, which is reinforced using cube towers. Students are then introduced to the game Guess My Rule in which several rules will be explored including doubling and halving a number. Lesson activities set the stage for students to use doubles plus one (or minus one) strategies for addition and subtraction.

Content in this Lesson

  • Representing and identifying even numbers.
  • Exploring the relationship between doubling and halving.
  • Representing doubles and halves using counters and number sentences [E1].
  • Using mental math strategies and reasoning strategies (e.g., using doubles) to solve addition and the related subtraction problems with sums up to 20 [E5].
  • Showing work [MPE5].
  • Generalizing a pattern as a rule.
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books
Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Students

20 connecting cubes

visual representations of doubles from Lesson 2

Materials for the Teacher

Display of Guess My Rule Machine Master or box decorated to look like a Guess My Rule Machine (Teacher Guide)
Unit 12 Assessment Record
chart paper

Materials Preparation

Prepare Chart for Part 1. Prepare a display on chart paper to use as students describe the visual representations of doubles made in Lesson 2. See Figure 1.
Prepare Chart for Part 2. Prepare a data table for display on chart paper to record number sentences for doubling [see Figure 5] and halving numbers. See Figure 2.

Figure 1: Blank chart describing doubling and halving


Figure 2: Data table for doubling and halving numbers
Prepare Targeted Practice for a Learning Center. Use the Guess My Rule Machine Master to prepare several different rules for students to determine. On some Masters the rule and input numbers can be given and students are asked to determine the output. On others the rule and output numbers can be given and students are asked to determine the input. See Summarizing the Lesson.

Assessment in this Lesson

Assessment Expectation Assessed

Doubles and Halves
Student Activity Book
Page 369
E1.
Represent doubles, near doubles, and halves using counters, pictures, and number sentences.
E5.
Use mental math strategies and reasoning strategies (e.g., using doubles, using ten, making ten) to solve addition problems with sums between 10 and 20 and the related subtraction problems.

Vocabulary in this Lesson