Problem-Solving Pioneers

Lesson Objective

By the end of this 45-minute lesson, students will confidently solve double-digit addition and subtraction problems involving regrouping, employing strategies such as place value understanding, visual aids, and peer collaboration. This lesson ties to California Common Core State Standards – Mathematics, Grade 3, particularly:
Domain: Operations & Algebraic Thinking

• 3.NBT.2: Add and subtract numbers up to 1000 fluently.

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Lesson Structure

1. Warm-Up Activity (5 minutes)

Objective: Activate prior knowledge of place value and regrouping.

• Write the following simple problems on the whiteboard:
  • 34 + 26
  • 48 - 19
  • 53 + 18

Procedure: Conduct a rapid-fire brain jog:

1. One student at a time solves one problem aloud while the rest gesture ‘thumbs up’ for agreement or ‘thumbs down’ if they think there’s a mistake.
2. Discuss place value briefly (e.g., “How did we think about the tens and ones to solve quickly?”).

Materials Needed: Whiteboard, markers

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2. Direct Instruction (10 minutes)

Objective: Explain and model addition and subtraction with regrouping using visual supports.

Addition with Regrouping

1. Write 37 + 26 on the board.
2. Ask, “What happens when the ones column adds up to more than 9?”
3. Solve it step-by-step while thinking aloud:
   • Add the ones (7 + 6 = 13, regroup 1 to the tens column).
   • Add the tens (3 + 2 = 5, then add the regrouped 1: Total = 6 tens).
   • Emphasise the importance of keeping “tens” and “ones” organised.

Subtraction with Regrouping

1. Write 51 - 29 on the board.
2. Explain borrowing by visualising the tens and ones columns:
   • “We don’t have enough ones to subtract 9, so we need to borrow 1 ‘ten’ from the tens column.”
   • Subtract step by step.

Engagement Strategy:

Use base-ten blocks or pre-drawn tens/ones boxes to demonstrate regrouping concepts.

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3. Guided Practice (10 minutes)

Objective: Students practise regrouping problems with peer collaboration and teacher support.

1. Pair students into teams of 2.
2. Distribute laminated cards containing problems like:
   • Addition: 45 + 37, 64 + 18, 52 + 29
   • Subtraction: 82 - 47, 61 - 38, 93 - 56

Procedure:

• Encourage students to use dry-erase markers to solve problems on the laminated cards.
• At each step, partners check their work and explain how they solved the problem.
• Teacher circulates the room, offering coaching where needed.

Materials Needed: Laminated problem cards, base-ten blocks, dry-erase markers.

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4. Independent Practice (15 minutes)

Objective: Reinforce understanding with an engaging worksheet.

Worksheet Title: “Treasure Map Math”

Theme: Each correct answer unlocks part of a pirate treasure map (fun and age-appropriate for 3rd graders).

Worksheet Problems: Mix of addition and subtraction with regrouping problems:

1. 46 + 29
2. 53 - 28
3. 38 + 24
4. 75 - 36
5. 68 + 17
6. 92 - 54

Added Challenge:

Students choose two problems to solve in their math journals using a number line or their own visual model (e.g., drawing place value boxes).

Materials Needed: Pirate-themed worksheet (see details below).

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5. Closing Activity (5 minutes)

Objective: Assess progress with a fun “math chant.”

• Teach students a regrouping chant to solidify concepts:

  “If there's 10 or more, make a group of tens,
  Pass one up, do it again!
  If borrowing's tough, it’s no big race,
  Take from tens, put it in ones place!”

• Then, display two regrouping problems on the board for students to solve as a whole group:

  • 68 + 27
  • 91 - 46

Encourage a mini “celebration” when the class solves them!

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Assessment Opportunities

• Observe how students solve problems during the guided and independent practice.
• Review completed worksheets and visual models in students’ math journals.

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Worksheet: Treasure Map Math

Below is the worksheet for the independent practice activity:

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Treasure Map Math

Name: ________________________________ Date: ______________

Directions: Solve each of the problems below. Each correct answer unlocks a new part of the pirate treasure map!

Addition Problems:

1. 46 + 29 = __________
2. 38 + 24 = __________
3. 68 + 17 = __________

Subtraction Problems:
4. 53 - 28 = __________
5. 75 - 36 = __________
6. 92 - 54 = __________

Challenge: Choose any TWO problems above. Solve them in your math journal using a number line or your own drawing.

(Optional Teacher Notes: Cut fun treasure map graphics into sections. For each correct problem, students receive part of the map to assemble!)

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Materials Checklist

• Whiteboard and markers
• Base-ten blocks or tens/ones visual aids
• Laminated problem cards and dry-erase markers
• Pirate-themed “Treasure Map Math” worksheet
• Coloured crayons for decorating finished worksheets.

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Teacher Reflection Post-Lesson

1. Did the pirate theme engage students and maximise participation?
2. Were students able to use place value strategies effectively?
3. Which students might require additional one-on-one support for regrouping?