Lesson plan

9. Connect composing and decomposing 5 (FP)

teaches Common Core State Standards CCSS.Math.Content.K.OA.A.1 http://corestandards.org/Math/Content/K/OA/A/1
teaches Common Core State Standards CCSS.Math.Content.K.OA.A.3 http://corestandards.org/Math/Content/K/OA/A/3
teaches Common Core State Standards CCSS.Math.Practice.MP1 http://corestandards.org/Math/Practice/MP1
teaches Common Core State Standards CCSS.Math.Practice.MP4 http://corestandards.org/Math/Practice/MP4
teaches Common Core State Standards CCSS.Math.Practice.MP7 http://corestandards.org/Math/Practice/MP7
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Lesson objective: Find number partners by decomposing and recomposing five.

This lesson helps to build procedural skill with decomposition. A math rack is used here because it supports subitization of the smaller parts of a total and organizes these pieces efficiently. This work develops students' understanding that a total can be decomposed into number partners in more than one way.

Students engage in Mathematical Practice 6 (Attend to precision) as they use the beads of the math rack to find number partners and select math language that will show how they know they have composed or decomposed five. Students may use count all or count on strategies to find the number that completes the total five and should be encouraged to verbally share their strategies. Additionally, students engage in Mathematical Practice 7 (Look for and make use of structure) as they consider the ways to compose and decompose five using a math rack.

Key vocabulary:

  • math rack
  • equal
  • minus
  • number partners
  • plus
  • take apart
  • total

Special materials needed:

  • math rack 
  • number cube
  • record sheet (or another option to record thinking)