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Parent guide · Grade 3 Math · Unit 3

Lesson 3.4 Commutative Property

Written for the parent. Read the Say this lines aloud as they are, or in your own words. Answers for you are marked Listen for.

At a glance

Time
5 sessions of 25–30 minutes
Goal
Use the commutative property to learn facts in pairs.
You need
  • Counters (dried beans, buttons or pebbles)
  • Dice
  • Pencil and crayons
Print
Worksheet A · Worksheet B · the lesson page

Steps

  1. Do this: Ask these out loud. Your child answers out loud; no paper needed.

    • Ask: “7 × 5” Listen for: 35
    • Ask: “10 × 10” Listen for: 100
    • Ask: “1 × 10” Listen for: 10
    • Ask: “2 × 9” Listen for: 18
    • Ask: “5 × 3” Listen for: 15

  2. Say this: “3 × 8 = 8 × 3. Turn the array on its side and the total is the same.”

    Say this: “Every fact you learn gives you its partner for free.”

    Say this: “Commutative property: the order of the factors does not change the product.”

  3. Show: 2 × 8 = ___

    Say this: “Twos are doubles: 8 + 8 = 16”

    Answer: 16

    Show: Find the missing number: ___ ÷ 6 = 6

    Say this: “Think multiplication: 6 × 6 = 36”

    Say this: “Check: 36 ÷ 6 = 6”

    Answer: 36

  4. Do this: Your child does these with you. Let them try first; help only after a real try.

    Ask: Write a multiplication fact for the array. How many in all?

    array of 2 rows and 5 columns

    Listen for: 2 × 5 = 10

    If stuck: There are 2 rows of 5.

    Ask: Write a multiplication fact for the array. How many in all?

    array of 2 rows and 7 columns

    Listen for: 2 × 7 = 14

    If stuck: There are 2 rows of 7.

    Ask: Write a multiplication fact for the array. How many in all?

    array of 5 rows and 2 columns

    Listen for: 5 × 2 = 10

    If stuck: There are 5 rows of 2.

    7 more practice items on the lesson page, and on Worksheet A and Worksheet B.

    • Thinking the property works for subtraction too.

  6. Roll two dice. Build that many rows and columns with beans or buttons, then say the fact: “4 rows of 6 is 24.” Keep a tally of facts you know instantly.

  7. Say this: “Tell me what you learned today. Show me with your hands or the counters if you like.”

    Listen for: Use the commutative property to learn facts in pairs.

  8. Skip count by 2s, 5s, 10s, 3s and 4s to the tenth multiple. Fact drill (one minute) on Fridays.

Spread over the week

5 sessions of 25–30 minutes. Stop while it is still going well.

  1. Session 1. Warm-up, then teach the new idea (steps 1 and 2).
  2. Session 2. Warm-up again, then show how with the examples.
  3. Session 3. Practice together, then play the game.
  4. Session 4. More practice on the worksheet, and the daily habit.
  5. Session 5. Quick check: narration and a few practice items. Move on when it is mostly right.