Thinkabara

🧮 3rd Grade · Math3.NBT.A.1Unit 5: Place value, rounding & adding/subtracting within 1,000

Estimating sums and differences

Google Classroom

🎯 Objective: Students estimate by rounding and check if answers are reasonable.

Lesson outline

  1. Estimate 389 + 214 by rounding to 400 + 200.
  2. Compare with the exact answer 603: is it reasonable?
  3. Find the wrong answer in three worked examples using estimates.
  4. Exit: estimate, then solve 512 − 289.

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

3.NBT.A.1

Common Core State Standards for Mathematics, Grade 3 — typical US scope & sequence

🏁 Unit goals

  • Round to the nearest 10 or 100
  • Fluently add and subtract within 1,000

✅ 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: Round to 10 and 100📚 All 3rd Grade skills🎮 Learning games⚡ Capy Live class quiz

🗓️ Plan the whole year like this

Add 3rd Grade Math to your free Lesson Planner: enter your timetable once and every period shows the next lesson, skipping weekends and school breaks.

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More lessons in “Place value, rounding & adding/subtracting within 1,000”

  1. Rounding to the nearest 10
  2. Rounding to the nearest 100
  3. Estimating sums and differences
  4. Adding within 1,000
  5. Subtracting within 1,000

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