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🧮 1st Grade · Math1.OA.C.5Unit 4: Subtraction strategies within 20

Subtraction on a number line

Google Classroom

🎯 Objective: Students subtract by hopping back or by finding the distance on a number line.

Lesson outline

  1. Model 12 − 3 with hops back.
  2. Model 12 − 9 by counting up from 9.
  3. Decide which is faster for each problem.
  4. Exit: 17 − 8.

Lesson 3 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

1.OA.C.5

Common Core State Standards for Mathematics, Grade 1 — typical US scope & sequence

🏁 Unit goals

  • Subtract within 20 using think-addition, counting back and making ten
  • Relate subtraction to addition

✅ 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 20🖨️ Worksheet: Addition Within 20🖨️ Worksheet: Subtraction Within 20📚 All 1st Grade skills🎮 Learning games⚡ Capy Live class quiz

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More lessons in “Subtraction strategies within 20”

  1. Think addition to subtract
  2. Subtract by making ten
  3. Subtraction on a number line
  4. Subtraction story problems
  5. Subtraction facts fluency

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