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Math lesson plan · 3rd grade (Year 4 in England) · 60 minutes

Multiply a two-digit number by a one-digit number by partitioning

Multiplication and division

CCSS 3.NBT.A.3CCSS 4.NBT.B.5England: Y3 Multiplication and divisionEngland: Y4 Multiplication and division

Objective and success criteria

Students will: Multiply a two-digit number by a one-digit number by partitioning.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Break apart a multiplication (distributive property); Multiply by multiples of 10

Leads to: Multiply a three-digit number by a one-digit number

Materials: Counters for arrays, Multiplication grid, Base-ten blocks, Mini whiteboards and pens, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Break apart a multiplication (distributive property); Multiply by multiples of 10). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. 4 × 80 = ? → 320Prompt: 80 is 8 tens.
  2. 8 × 80 = ? → 640Prompt: 80 is 8 tens.
  3. 3 × 50 = ? → 150Prompt: 50 is 5 tens.

Hook · 6 min

  • Show an array of chairs, eggs or windows and ask how many there are without counting one by one.
  • Share the objective: Multiply a two-digit number by a one-digit number by partitioning. Read the success criteria together.

I do: model it · 12 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: 22 × 5 = ?
  • Step 1: 20 × 5 = 100
  • Step 2: 2 × 5 = 10
  • Step 3: 100 + 10 = 110
  • Answer: 110
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. 14 × 8 = ? → 112Prompt: Split 14 into tens and ones: 10 + 4.
  2. There are 7 packs with 97 stickers in each. How many stickers are there altogether? → 679Prompt: You need 7 × 97.

You do: independent practice · 17 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. There are 5 boxes with 40 pencils in each. How many pencils are there altogether? → 200Prompt: You need 5 × 40.
  2. 28 × 8 = ? → 224Prompt: Split 28 into tens and ones: 20 + 8.

Watch out for

  • Thinking multiplying always makes a number bigger.
  • Dropping a zero in long multiplication when moving to the tens row.

Support and stretch

Support

  • Review first: Break apart a multiplication (distributive property).
  • Use concrete materials: counters for arrays.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Multiply a three-digit number by a one-digit number.
  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-3.

Free lesson plan from eurekami.com/lesson-plan-builder

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Multiply a two-digit number by a one-digit number by partitioning

Name

Date

Score/ 8

  1. Question 1

    13 × 4 = ?

    Answer

  2. Question 2

    There are 8 packs with 90 stickers in each. How many stickers are there altogether?

    Answer

  3. Question 3

    Kofi worked out 38 × 6 as 30 × 6 + 8 = 188. What mistake was made, and what is the right answer?

    Answer

  4. Question 4

    36 × 3 = ?

    Answer

  5. Question 5

    There are 8 tubs with 93 crayons in each. How many crayons are there altogether?

    Answer

  6. Question 6

    Ines worked out 29 × 4 as 20 × 4 + 9 = 89. What mistake was made, and what is the right answer?

    Answer

  7. Question 7

    16 × 4 = ?

    Answer

  8. Question 8

    There are 7 tubs with 86 crayons in each. How many crayons are there altogether?

    Answer

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Answer key: Multiply a two-digit number by a one-digit number by partitioning

  1. 1. 52

  2. 2. 720

  3. 3. 228

  4. 4. 108

  5. 5. 744

  6. 6. 116

  7. 7. 64

  8. 8. 602