Lesson plan

10. Solve addition and subtraction problems involving mass (A)

  • From K-5 Math Companion Curriculum
  • Created by
  • Standards
  • Tags:
teaches Common Core State Standards 3.MD.A.2 http://corestandards.org/Math/Content/3/MD/A/2
teaches Common Core State Standards MP1 http://corestandards.org/Math/Practice/MP1
teaches Common Core State Standards MP4 http://corestandards.org/Math/Practice/MP4
teaches Common Core State Standards MP5 http://corestandards.org/Math/Practice/MP5
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Lesson objective: Solve problems using the number line to show addition and subtraction strategies.

This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a real-life situation. Students are asked to show on the number line a correct strategy for solving the problem.

Note that in the number selection in this lesson asks students to add and subtract beyond 1000, exceeding the grade-level expectations for Grade 3. An alternate task with addends within 1,000 is included in the Additional Materials. 

Key Concept students will use: 

  • representations and drawings to solve one-step situational problems involving addition and subtraction of mass.

Skills students will use:

  • place value understanding to add and subtract using a variety of strategies (Grade 3, Unit 3)
  • a number line to solve many types of addition and subtraction problems (Grade 2, Unit 2)
  • representations of a three-digit number as hundreds, tens, and ones, from left to right. (Grade 2, Unit 6)

Students engage in Mathematical Practice 1 (make sense of problems and persevere in solving them) as they use the number line to understand the problem and the meaning of the question. Students engage in Mathematical Practice 4 (model with mathematics) as they write number equations to describe how they used the number line.

Key vocabulary: 

  • grams
  • kitchen gram scale
  • number line
  • pan balance

Special materials needed:

  • kitchen gram scale
  • number line for demonstration (0 to 2,000)
  • pan balance scale and gram weights