Multiply 1 by 3 Digits

Overview

This lesson is the 3rd in a short unit on mastering multiplication concepts. Students will multiply 1-digit numbers by 3-digit numbers and use the standard algorithm with place value reasoning and step-by-step work.

Learning intentions

Students will be able to:

• Multiply a 1-digit whole number by a 3-digit whole number using the standard algorithm.
• Explain each partial product and where it lands using place value (hundreds, tens, ones).
• Check whether their answer is reasonable using estimation based on compatible numbers.

Learning outcome (unit-aligned): Students will complete 1-digit by 3-digit multiplication problems with 80% accuracy.

Success criteria

• I can write a 1-digit by 3-digit multiplication as step-by-step standard algorithm work (including partial products).
• I can correctly place each partial product according to place value.
• I can explain at least one step of my computation clearly (what I multiplied and why).
• I can use an estimate to judge whether my final product is reasonable.

Curriculum links

• Number and Operations in Base Ten — fluently multiply multi-digit whole numbers using the standard algorithm.
• Number and Operations in Base Ten — find and illustrate whole-number quotients using place value and area/array models (used here to support place-value reasoning when checking work).
• Number and Operations in Base Ten — explain that digits represent different values depending on their place (ones, tens, hundreds).
• Operations and Algebraic Thinking — write and interpret expressions that represent multiplication relationships (used informally during estimation and reasoning).

Lesson structure (30 minutes)

1. 0–5 min · Bell work + review. Teacher posts 2 quick multiplication problems from the last lesson and one “spot the mistake” sample; students correct silently, then discuss with a partner.

• Students compute, underline where the error happened, and record the corrected steps.

2. 5–10 min · Homework correction (teacher-led). Teacher reviews common errors from homework, showing a worked solution that highlights partial products and place value.

• Students update their own work using a checklist: “Did I multiply correctly? Did I align by place value? Did I add partial products?”

3. 10–18 min · Direct teach: standard algorithm for 1×3 digits. Teacher demonstrates 1-digit × 3-digit using an expanded algorithm with a clear template: Example: 6 × 243

• Students watch the teacher annotate each partial product: 6×3 (ones) = 18 → write 8, carry 1 6×4 (tens) = 24 plus carry 1 = 25 → write 5, carry 2 6×2 (hundreds) = 12 plus carry 2 = 14 → write 14 to the left
• Teacher emphasizes: “Each digit’s position determines what you’re really multiplying.”
• Students complete a second example together: 7 × 315, using the same step-by-step format.

4. 18–26 min · Guided practice (two sets). Teacher circulates while students work on 6 problems in two rounds; round 1 focuses on accurate partial products, round 2 adds a quick estimate check.

• Students solve:
• Round 1 (3 problems): focus on the standard algorithm work.
• Round 2 (3 problems): before multiplying, estimate (e.g., 1-digit × 3-digit by rounding to the nearest hundred or using compatible numbers like 300) and then solve.

5. 26–30 min · Exit ticket + quick teacher check. Teacher collects a short exit ticket: 1 problem + 1 “reasonableness” sentence.

• Students answer: “My estimate was about ___, so my answer of ___ makes sense because ___.” and show their steps.

Resources

• Student multiplication practice sheet (6 guided problems + 1 exit ticket), with space for steps
• Pencil, eraser, and lined paper for work shown
• Place value chart (hundreds/tens/ones) for teacher display
• Sticky notes or mini whiteboards for quick estimation checks
• Sample “spot the mistake” from previous homework
• Timer or agenda slide for pacing

Assessment

• During bell work and homework correction: listen for whether students align partial products by place value.
• During guided practice: check for correct carrying and correct placement of final digits.
• Exit ticket: accuracy on the product and a brief, reasonable explanation using an estimate.

Differentiation

• Support for students needing extra structure:
• Provide a partially filled algorithm template (lines for partial products, carry notes, and final sum).
• Offer sentence starters for explanations: “I multiplied __ by __, so the ones digit is __.”
• Encourage use of a place value chart while aligning digits.
• Extension for students ready for more challenge:
• Add a challenge set with one problem that includes a carry through multiple places (e.g., 8 × 396) and ask for an additional estimation strategy.
• EAL/SEN considerations:
• Keep language consistent: “partial product,” “place value,” “carry,” “ones/tens/hundreds.”
• Pair with a supportive partner during Round 1; allow extra time for Round 2 estimate check without penalizing writing length.
• Accuracy goal scaffolding:
• If a student misses the first carry step, require redoing only that step and the final addition, then re-check with an estimate.