School Launch

Parent guide · Grade 1 Math · Unit 6

Lesson 6.4 Subtracting Tens

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 20–25 minutes
Goal
Subtract multiples of 10.
You need
  • A few real coins
  • 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: “1 + 4” Listen for: 5
    • Ask: “4 + 8” Listen for: 12
    • Ask: “1 + 3” Listen for: 4
    • Ask: “5 + 1” Listen for: 6
    • Ask: “7 + 5” Listen for: 12

  2. Say this: “80 − 30: 8 tens take away 3 tens is 5 tens, 50.”

    Say this: “67 − 20 = 47: the tens go down by 2, the ones stay.”

    Say this: “Subtract tens: take away whole tens; the ones do not change.”

  3. Show: 67 − 30 = ___

    Say this: “Take away the tens: 67 − 30 = 37”

    Answer: 37

    Show: Gideon had 96 men. He sent 30 home. How many men stayed?

    bar model

    Say this: “Unknown: how many are left.”

    Say this: “Bar model: the whole is 96; one part is 30; the other part is unknown.”

    Say this: “Equation: 96 − 30 = ?”

    Say this: “96 − 30 = 66”

    Say this: “Answer: 66 men stayed.”

    Answer: 66 men. 66 men stayed.

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

    Ask: 60 − 10 = ___

    Listen for: 50

    If stuck: Take away the tens: 60 − 10 = 50

    Ask: 50 − 30 = ___

    Listen for: 20

    If stuck: Take away the tens: 50 − 30 = 20

    Ask: 60 − 20 = ___

    Listen for: 40

    If stuck: Take away the tens: 60 − 20 = 40

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

    • Changing the ones digit.

  6. Price toys at 10¢, 20¢ … 90¢. Your child pays with dimes and says the total of two toys, then the change from $1.

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

    Listen for: Subtract multiples of 10.

  8. Count by tens from any number: 3, 13, 23 … and back down.

Spread over the week

5 sessions of 20–25 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.