Lesson 90: Subtracting small numbers

🧮 MATH (40 Lessons) • 🟢 A. Numbers and Counting

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Objective

I can subtract two small numbers. I can use counters, a number line, and a subtraction sentence to show how many are left.

Materials

Mini-lesson — What does it mean to subtract?

When you subtract, you take some away from a group. We use words like minus, take away, left, and difference.

Subtracting with counters

  • Start with 8 toy blocks.
  • Take away 3.
  • Count how many are left: 8 − 3 = 5.

Subtracting on a number line

  • Start at the first number.
  • Jump to the left for the number you are taking away.
  • Where you land is how many are left.
  • Example: 7 − 2 → start at 7, jump left 2 → land on 5.

Writing a subtraction sentence

  • A subtraction sentence uses − and =.
  • Example: 6 − 1 = 5.
  • We read it as “six minus one equals five”.

In this lesson, stay mostly within 20. Use pictures, toys, and number lines to make each subtraction sentence easy to understand.

Picture strip: Subtraction with blocks and number line

Counters — 8 − 3

Number line — 7 − 2

Guided Practice — Subtract with counters and a number line

You will use real counters and a number line to subtract two small numbers. Then you use the tracing pad to write the most important subtraction words.

  1. Pick two numbers: Choose two numbers from 0–10 (for example 8 and 3).
  2. Build with counters: Start with 8 toy blocks. Take away 3. Count how many are left.
  3. Show it on the line: On your number line, start at the first number. Jump to the left for the number you are taking away.
  4. Write the subtraction sentence: In your notebook, write 8 − 3 = 5 (or your own example).
  5. Try a new pair: Pick two new numbers within 10 (for example 7 and 2) and repeat.
  6. Use the tracing pad: Trace two short words (for example minus and left) or trace a number (like 7).
  7. Add a tiny picture: Next to take away, draw toys disappearing. Next to left, circle the toys that remain.
Tracing Pad
Tracing snapshot for print
Tip: After you trace your words, write a short sentence, such as "I take away to find what is left." Draw a tiny subtraction jump on the number line below it.

Practice 1 — Drag & Drop: Complete the subtraction

Look at the bead bar and the number sentence. Start with the red beads (first number), take away the blue beads (second number), and drag the correct answer into the box. Each question has one empty box and three choices.

1) Bead bar:

Number sentence: 5 − 2 = [ ]

2 3 4

2) Bead bar:

Number sentence: 7 − 3 = [ ]

5 4 3

3) Bead bar:

Number sentence: 4 − 2 = [ ]

1 2 3

4) Bead bar:

Number sentence: 9 − 3 = [ ]

5 6 7

5) Bead bar:

Number sentence: 3 − 2 = [ ]

1 2 0

6) Bead bar:

Number sentence: 6 − 2 = [ ]

5 4 3

7) Bead bar:

Number sentence: 8 − 3 = [ ]

4 5 6

8) Bead bar:

Number sentence: 10 − 3 = [ ]

6 7 8

9) Bead bar:

Number sentence: 5 − 3 = [ ]

1 2 4

10) Bead bar:

Number sentence: 3 − 3 = [ ]

1 0 2

Practice 2 — Tap grid: Choose the correct difference

For each fact, look at the bead bar, then tap the correct answer. Think: “start − take away = left”.

1) 6 − 2 = ?

Bead bar:

2) 8 − 5 = ?

Bead bar:

3) 7 − 1 = ?

Bead bar:

4) 9 − 4 = ?

Bead bar:

5) 5 − 0 = ?

Bead bar:

6) 10 − 6 = ?

Bead bar:

7) 4 − 1 = ?

Bead bar:

8) 9 − 5 = ?

Bead bar:

9) 7 − 4 = ?

Bead bar:

10) 6 − 3 = ?

Bead bar:

Practice 3 — Number line: Subtraction as jumps back

Use the number line to show subtraction as jumps back. Start at the first number and jump back the second number of steps. Tap the number where you land.

Think: “start − jumps back = landing place”.

1) 6 − 2 = ?

Start at 6. Jump 2 steps back on the number line. Where do you land?

2) 5 − 2 = ?

Start at 5. Jump 2 steps back.

3) 4 − 3 = ?

Start at 4. Jump 3 steps back.

4) 8 − 3 = ?

Start at 8. Jump 3 steps back.

5) 7 − 5 = ?

Start at 7. Jump 5 steps back.

6) 4 − 4 = ?

Start at 4. Jump 4 steps back.

7) 9 − 6 = ?

Start at 9. Jump 6 steps back.

8) 3 − 2 = ?

Start at 3. Jump 2 steps back.

9) 10 − 4 = ?

Start at 10. Jump 4 steps back.

10) 5 − 3 = ?

Start at 5. Jump 3 steps back.

Quick Check — Subtracting small numbers

Answer each question about subtracting small numbers. You may use counters or a number line to help you.

1) What does it mean to subtract?

When we subtract, we take away and find what is left.

2) What is 5 − 2?

5 take away 2 leaves 3.

3) What is 7 − 4?

7 minus 4 equals 3.

4) On a number line, when you subtract you jump:

Subtracting moves left to smaller numbers.

5) What is the difference in 9 − 5 = 4?

The difference is the answer, which is 4.

6) What is 10 − 8?

10 take away 8 leaves 2.

7) You have 6 toy cars and lose 1. Which sentence shows this?

You are taking 1 away from 6, so 6 − 1 = 5.

8) What is 1 − 1?

One take away one leaves zero.

9) Which sign do we use when we subtract?

The minus sign (−) means subtract.

10) What is 9 − 4?

9 take away 4 leaves 5.

11) You start at 8 on a number line and jump 3 steps left. Where do you land?

8 − 3 = 5, so you land on 5.

12) What is 12 − 10?

12 take away 10 leaves 2.

13) Which sentence is true?

7 take away 7 leaves 0.

14) You have 10 crayons and give away 5. How many are left?

10 − 5 = 5.

15) Why do we use a number line when we subtract?

Jumps on the number line help us see how we got the answer.

Assessment (parent/teacher)

Exit ticket (student)

Next time I will practise…

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