Adding Two-Digit Numbers

Objective

Students will be able to accurately add two-digit numbers involving simple regrouping by applying place value understanding and addition strategies.

Common Core State Standards (CCSS) Alignment

• CCSS.MATH.CONTENT.2.NBT.B.5: Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
• CCSS.MATH.CONTENT.2.NBT.B.7: Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method.

Materials Needed

• Whiteboard and markers
• Base-ten blocks (units and rods)
• Number cards (0-9)
• Place value mats (ones and tens columns)
• Small blank whiteboards and markers for each student
• Sticky notes
• “Regrouping Robot” cutout (a fun mascot for regrouping steps)

Duration

45 minutes

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Lesson Breakdown

1. Warm-up Activity: Place Value Dance (5 minutes)

• Purpose: Activate prior knowledge of place value (tens and ones).
• Activity: Students stand, and the teacher calls out a two-digit number (e.g., 34).
• Students act it out by holding up “tens” rods with one hand and “ones” fingers with the other hand.
• Teacher reinforces by asking, “How many tens? How many ones?”
• This kinesthetic approach helps internalize place value concepts before moving to addition.

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2. Introduction to Adding with Regrouping (10 minutes)

• Use base-ten blocks and place value mats to visually model:
  Example: 27 + 46
  • Put 27 using 2 rods (tens) and 7 units (ones) on the mat.
  • Add 46 using 4 rods and 6 units.
  • Start with the ones column: 7 + 6 = 13 units.
  • Show regrouping: 13 units mean 1 rod (ten) to move to tens column and 3 remain in ones.
  • Add tens: 2 + 4 + 1 (from regrouping) = 7 rods.
  • Total: 73
• Emphasize the step-by-step process with the Regrouping Robot mascot highlighting each step with sticky note prompts (e.g., “Add ones!”, “Regroup!”, “Add tens!”).
• Ask students to repeat the process aloud with a partner.

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3. Guided Practice on Mini Whiteboards (10 minutes)

• Write problems on the board:
  34 + 28
  45 + 37
  62 + 29
• Students use individual whiteboards and base-ten blocks if needed.
• Teacher circulates, providing help and encouraging proper regrouping steps.
• Have students explain their regrouping steps verbally to the teacher or partner.

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4. Collaborative “Regrouping Relay” Game (10 minutes)

• Place number cards 0-9 face down on the table.
• Each team of two students draws two cards for the first number and two cards for the second number (e.g., cards drawn: 5, 3 and 4, 6 forming 53 + 46).
• Students work together to model the problem with base-ten blocks on place value mats and record answer on shared mini whiteboard.
• The “Regrouping Robot” cheer is shouted when they complete correctly, emphasizing teamwork and fun.
• Rotate pairs so each child practices several problems.

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5. Closing and Assessment (5 minutes)

• Quick oral quiz: Ask each student one two-digit addition problem with regrouping to solve verbally.
• Example: “What is 58 + 27?”
• Confirm correct explanation of regrouping steps (“What did you do with the ones? How many tens did you add?”).
• Give positive feedback and identify a student’s answer to demonstrate for the class (if time).

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Differentiation and Extensions

• For struggling learners: Use additional base-ten block practice, emphasize counting units carefully.
• For advanced learners: Provide 3-digit addition problems without regrouping or explore subtraction with regrouping.
• Use a story problem involving money (e.g., adding 47 cents and 36 cents) to connect math to real-world contexts.

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Reflection

Ask students to share one thing they learned about regrouping and how the Regrouping Robot helped them remember the steps.

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This lesson plan ensures hands-on learning, collaboration, and adhering to the CCSS standards for fluency with two-digit addition and regrouping, tailored well for a small class of 6 second graders in an engaging 45-minute session.