UNIT PREPARATION

Display the class number line (0–130) where students can see and reach it with a pointer.

Attach a desk number line (0–40) to each student's desk to use throughout the year.

Display the Math Practices page where all students can see it.

Attach copies of the Desk-Size 100 Chart to students' desks or folders to use throughout the year in class and at home. See the Unit 9 Lesson 7 Materials Preparation.

Copy the Ten Frames and Number Line Master and the 100 Chart Master back-to-back for easy access to these tools during class and at home. See the Lesson 1 Materials Preparation.

Display the Comparison Symbol Chart from Unit 8 Lesson 5.
Gather small brown paper bags. See Lesson 8 Materials Preparation.

Have the following tools readily available for the Daily Practice and Problems items in this unit:

LESSON SESSIONS DESCRIPTION SUPPLIES

LESSON 1

Invented Strategies

 2–3 During a strategy session, students review strategies they used in previous lessons, develop more strategies for sums greater than 10, and record them on an invented strategies chart. Then they solve problems with larger sums and describe the strategies and tools they use.
  • connecting cubes
  • number lines
  • chart paper

LESSON 2

Seeing Doubles

 1–2 Students create visual representations of doubling a number then create a table of doubles. The class brainstorms a list of familiar items that come in pairs then think of doubles number sentences to reflect their examples.
  • paintbrushes and paint, hole punches, or scissors
  • paper
  • chart paper
  • connecting cubes

LESSON 3

Doubles and Halves

 2 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.
  • connecting cubes
  • visual representations of doubles from
    Lesson 2
  • chart paper

LESSON 4

Doubles +1, Doubles −1

 1–2 Students categorize answers to doubles problems as even or odd. They discuss how the category of their answers changes when they add 1 to (or take away 1 from) their original answers. Students demonstrate doubles +1, and doubles −1 problems by building two-column towers made of connecting cubes. They also form number sentences based on their cube models.
  • connecting cubes
  • clear plastic spinner or paper clip and pencil
  • chart paper

LESSON 5

Making Ten

 2–3 Students use their prior knowledge of place value of numbers from 10 to 20 and the partitions of ten to develop strategies for adding numbers with sums in the teens. They learn to break apart numbers to make ten.
  • connecting cubes
  • number lines
  • chart paper

LESSON 6

Thinking about Number Sentences

 2 Students use a variety of methods to determine whether number sentences are true. They find missing numbers so that the expressions on both sides of the equal sign represent the same numerical value.
  • connecting cubes
  • number lines
  • chart paper

LESSON 7

Practice Strategies for Larger Numbers

 2–3 Students revisit the Invented Strategies chart and discuss which strategies seem better suited to solve each fact. They summarize those strategies into an Addition Strategies Menu for Larger Numbers. Students then choose a practice that will help them develop reasoning-from-known-facts strategies to solve addition facts.
  • Invented Strategies chart from Lesson 1
  • connecting cubes
  • clear plastic spinner or paper clip and pencil
  • chart paper
  • tape or glue

LESSON 8

How Many in the Bag

 2–3 Students practice strategies for subtracting from larger numbers as they play the game How Many in the Bag. They discuss invented strategies used in the game, including using fact families to help solve subtraction problems.
  • connecting cubes
  • paper bags
  • number lines
  • Invented Strategies chart from Lesson 1

LESSON 9

Subtraction Strategies

 1 Students solve comparison problems presented in the story How Many Blue Birds Flew Away by Paul Giganti, Jr. They use addition strategies (making 10, using doubles, using ten) to solve related subtraction problems and then add new subtraction strategies to the Invented Strategies chart from Lesson 1.
  • How Many Blue Birds Flew Away by Paul Giganti, Jr.
  • Invented Strategies chart from Lesson 1
  • number lines
  • connecting cubes

LESSON 10

Practice Subtraction Strategies

 1–2 Students build a Subtraction Strategies Menu and discuss which strategies seem to be better suited for different subtraction facts. Students then self-assess their confidence with counting and reasoning strategies for subtraction to choose appropriate practice for developing fluency with these subtraction strategies.
  • connecting cubes
  • number lines
  • chart paper

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Essential Titles

  • Giganti, Paul. How Many Blue Birds Flew Away?: A Counting Book with a Difference. Greenwillow Books/HarperCollins Publishers, New York, 2005.

Suggested Titles

  • Hong, Lily Toy. Two of Everything. Albert Whitman and Company, Toronto, 1993.