Subtraction Problem Help

Overview

This short intervention focuses on solving a one-step subtraction word problem using concrete representations and a number sentence, then checking the answer using the inverse operation. It is designed for a student who finds subtraction word problems difficult.

Learning intentions

WALT: solve one-step subtraction word problems using objects/pictures and write the matching subtraction number sentence.

WALT: use inverse operations to check the answer is reasonable.

Success criteria

• I can identify what the question is asking (how many are left / how many more/less).
• I can model the subtraction using counters or a bar model.
• I can write the correct subtraction number sentence.
• I can check my answer by adding back (inverse operation).

Curriculum links

• Number — addition and subtraction (KS1-KS2): solve one-step problems that involve addition and subtraction, using concrete objects and pictorial representations, and missing number problems.
• Number — addition and subtraction (KS1-KS2): estimate and use inverse operations to check answers to a calculation.

Lesson structure (30 minutes)

1. 0–5 min · Warm-up (spot the operation). Teacher shows 2 quick word statements on paper (e.g., “I have 9 sweets and I eat 3.” / “I have 9 sweets and I get 3.”) and asks: “Which one means we take away?” Student points to the correct statement and explains briefly (or uses a sentence starter: “This is taking away because…”).

2. 5–12 min · Model a one-step subtraction problem. Teacher reads a single subtraction word problem aloud twice (e.g., “There are 10 balloons. 4 pop. How many are left?”), then models with counters: start with 10, cross out/take away 4, count what remains. Student follows on a mini whiteboard or with the same counters, counting remaining objects and saying the answer.

3. 12–18 min · Build the number sentence. Teacher writes the number sentence while the student watches: 10 - 4 = 6 and highlights the words “left/remaining” as take-away signals. Student copies the number sentence and fills missing parts if needed (e.g., 10 -? = 6) using the model.

4. 18–24 min · Guided practice (second problem, same structure). Teacher gives a new one-step subtraction problem with a similar context (e.g., “There are 12 stickers. I use 5. How many are left?”). Student models independently but with teacher prompting: “What do we start with? What are we taking away? What’s left?” Student draws a simple picture/bar (or uses counters) and writes the subtraction sentence.

5. 24–29 min · Check using inverse operation. Teacher teaches a simple check routine: if the answer is start - taken = left, then check by doing left + taken = start. Student performs the check using the numbers from their problem and states: “My check works, so my answer is likely correct” (or corrects if it doesn’t).

6. 29–30 min · Exit reflection (quick confirm). Teacher asks one final question: “Which word in the problem told you to subtract?” Student answers using a keyword bank (left/remaining/take away) or points to the word on the printed problem.

Resources

• Counter set (or plastic/foam counters) and small tray
• Mini whiteboard, pen, and wipe cloth
• Printed one-step subtraction word problems (2 teacher-led + 1 for student)
• Number sentence cards (e.g., __ - __ = __) for scaffolding
• Ten-frames or simple bar model templates
• Keyword strip: left / remaining / take away / fewer / pop / use / spend
• Optional: a basic “Check: add back” prompt card

Assessment

• Teacher observes whether the student correctly identifies “take away” from the context words.
• Teacher checks the subtraction modelling matches the story (counters removed correctly).
• Teacher listens for correct number sentences and verifies the inverse check is attempted.
• If needed, teacher records: correct answer, correct model, correct number sentence, correct check.

Differentiation

• Support:
• Use sentence starters: “We start with…”, “We take away…”, “We have… left.”
• Provide a visual checklist: Start number → Take away → Left.
• Offer a reduced-choice format (two word problems: one addition, one subtraction) to ensure correct operation selection.
• Keep numbers within a manageable range (e.g., 10–20) and use ten-frames/counters to reduce working memory load.
• Intervention pace:
• Pause after reading, then prompt only one step at a time.
• Allow the student to verbalise the counting sequence before writing the equation.
• Extension (for faster accuracy or confidence):
• Provide a second subtraction problem where the missing number is taken away (e.g., “There are 12. 8 are left. How many were taken away?”) while still using counters and the check-add-back method.
• Ask the student to estimate before solving (“Will the answer be less than 12 by a little or a lot?”) and then compare with the model.