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🧮 2nd Grade · Math2.NBT.B.9Unit 6: Adding & subtracting within 1,000

Explain your strategy

Google Classroom

🎯 Objective: Students explain why addition and subtraction strategies work using place value.

Lesson outline

  1. Compare two students’ methods.
  2. Write an explanation together.
  3. Solve and explain in pairs.
  4. Exit: explain one answer in writing.

Lesson 5 of 5 in this unit. In the Lesson Planner this lesson takes 1–3 class periods depending on your timetable: day 1 introduce & model, then practice, small-group reteach and a quick check.

📐 Standard

2.NBT.B.9

Common Core State Standards for Mathematics, Grade 2 — typical US scope & sequence

🏁 Unit goals

  • Add and subtract within 1,000 using models and place value strategies
  • Explain why strategies work

✅ Check for understanding

End with the exit ticket in the outline. Sort answers into got it / almost / not yet and start the next lesson with a 5-minute reteach for the “not yets”.

Practice & resources on Thinkabara

🎯 Practice: Add & subtract within 100🎯 Practice: Place value to 1,000🖨️ Worksheet: Two-Digit Addition Within 100🖨️ Worksheet: Two-Digit Subtraction Within 100📚 All 2nd Grade skills🎮 Learning games⚡ Capy Live class quiz

🗓️ Plan the whole year like this

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More lessons in “Adding & subtracting within 1,000”

  1. Adding three-digit numbers
  2. Regrouping in addition
  3. Subtracting three-digit numbers
  4. Regrouping in subtraction
  5. Explain your strategy

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