Mission Subtract Whole Numbers

Overview

In this 3rd of 4 unit lessons, students practice subtracting whole numbers with regrouping. They use number lines and visual models (place value drawings and equations) to make their thinking clear and accurate.

Learning intentions

• Students will be able to subtract multi-digit whole numbers using regrouping.
• Students will choose and explain strategies using number lines and visual models.
• Students will connect subtraction to place value and the meaning of “take away” and “compare.”
• Students will check their work using estimation and inverse operations.

Success criteria

• I can subtract whole numbers with regrouping and write a correct subtraction equation.
• I can model the subtraction with a number line or a visual/part-part-whole diagram.
• I can explain how regrouping helps me subtract across place values.
• I can verify my answer using estimation or addition.

Curriculum links

• Understanding subtraction as “take away” and “compare” within whole numbers.
• Performing multi-digit addition and subtraction with regrouping using place value reasoning.
• Using place value understanding to explain and represent operations.
• Solving word problems involving subtraction and interpreting the context.

Lesson structure (30 minutes)

1. 0–4 min: Mission launch + activation

• Show a quick problem: “There are 37 stickers. You give away 15. How many are left?”
• Students turn-and-talk: “What strategy would help—number line, model, or algorithm?”

2. 4–10 min: Guided model—visual parts to regroup

• Teacher models 37 − 15 using a place value representation (tens and ones).
• Demonstrate regrouping: exchange 1 ten into 10 ones, then subtract ones, then tens.
• Students echo the steps while the teacher connects each step to the visual model.

3. 10–16 min: Guided model—number line jumps

• Draw a number line from 22 (or the starting value) and show jumps back 15 to reach the answer.
• Use two-color/structured jumps for tens and ones (for example: jump back 10, then back 5).
• Students record the equation and label the landing point as the final count.

4. 16–23 min: Practice rotation (15 students, small groups)

• Set up two stations and one whole-class check. Rotate groups after about 3–4 minutes:
• Station A (hands-on/visual): base-ten blocks or place value drawings; solve 3 subtraction problems with regrouping.
• Station B (number line): solve the same type of problems using number line jumps; show at least one equation and one model.
• Teacher circulates, selecting 1–2 students’ models to share strategies and fix common regrouping errors.

5. 23–28 min: Quick assessment (independent)

• Students complete a short set of 2 problems:
• One “take away” word problem (e.g., 64 − 27).
• One direct equation with regrouping (e.g., 50 − 19).
• Require each student to show either a number line or a visual model plus the subtraction equation.

6. 28–30 min: Exit ticket + check

• Exit ticket prompt: “Explain regrouping in one sentence. How does it help your subtraction?”
• Collect work; look for correct regrouping and accurate model-to-equation alignment.

Resources

• Base-ten blocks or place value drawings (tens and ones).
• Number line templates (with 0–100 options).
• Small problem cards for stations (regrouping across ones, e.g., 3-digit may be introduced only if already used in the unit).
• Student recording sheet: Model → Equation → Answer.
• Whiteboards or scrap paper for quick checking.
• Optional digital practice platform for extensions (teacher-prepared subtraction items with regrouping).
• Timers for rotation management.
• Anchor chart: “How to subtract with regrouping” (visual model steps and number line jumps).

Assessment

• During station rotation: teacher checks for correct regrouping and whether the model matches the equation.
• Independent quick assessment: accuracy of answers and completeness of modeling (number line or visual model).
• Exit ticket: clarity of explanation connecting regrouping to place value.

Differentiation

• Support (scaffolds for students who need it)
• Provide a partially completed number line (starting point and first jump already marked).
• Offer a “regrouping frame” showing how many ones you have after exchanging one ten.
• Allow students to use base-ten blocks before writing the equation.
• Additional practice (for students needing more repetition)
• Provide one extra similar problem at the same station with fewer numbers changed, focusing on the regrouping step.
• Extension (for advanced learners)
• Give a multi-step subtraction word problem that includes both “take away” and “compare,” requiring students to choose an efficient strategy (number line or model) and justify why it works.
• Challenge: “Create your own subtraction problem that requires regrouping and include a model and answer.”
• Optional digital platform set to harder regrouping contexts with immediate feedback.
• EAL/SEN supports
• Use sentence stems: “First I regrouped because… Then I subtracted… My answer is…”
• Preview vocabulary in context (take away, left, difference) with visuals.
• Keep directions short and repeat the station purpose while pointing to the model types.

Extension Activity (optional)

• Students write a short story involving subtraction with regrouping (4–6 sentences).
• Include:
• A setting (school, store, game, animals).
• Two numbers where regrouping is required.
• The subtraction equation and one model reference (number line or visual).
• Teacher provides a prompt such as: “Write about something that decreases, and include how many were starting and how many were left.”