Addition and subtraction – ways to make a number – up to 20

key notes :

🌟 Understanding Numbers up to 20

  • Numbers from 0 to 20 can be made using different combinations.
  • Example: 10 can be made as
    → 5 + 5
    → 6 + 4
    → 7 + 3

➕ Making Numbers Using Addition

  • Addition means putting numbers together.
  • We can make the same number in many ways.

Examples:

  • 8 = 4 + 4
  • 8 = 5 + 3
  • 8 = 6 + 2

👉 One number → many addition pairs

➖ Making Numbers Using Subtraction

  • Subtraction means taking away.
  • We can also make numbers by subtracting.

Examples:

  • 8 = 10 − 2
  • 8 = 9 − 1
  • 8 = 12 − 4

🔄 Fact Families (Addition & Subtraction Together)

  • Addition and subtraction are related.

Example (for 6, 2, 4):

  • 2 + 4 = 6
  • 4 + 2 = 6
  • 6 − 2 = 4
  • 6 − 4 = 2

👉 These are called a fact family

🔢 Number Bonds

  • A number bond shows how a number is split into two parts.

Example:

  • 10 → 7 + 3
  • 10 → 6 + 4

👉 Helps students see parts and whole

🧠 Use of Fingers, Objects, and Number Line

  • Use fingers, beads, or toys to count.
  • Use a number line (0–20) to add or subtract.

🎯 Important Tips

  • Start from bigger number while adding.
  • Count forward for addition, backward for subtraction.
  • Practice number pairs that make 10 and 20.

Learn with an example

🎯 Select all of the ways to make 18.

  • 7 + 11
  • 14 + 6
  • 10 + 9
  • 19 − 1
  • These are ways to make 18:
  • 7 + 11 = 18
    19 − 1 = 18
  • These are not ways to make 18:
  • 14 + 6 = 20
    10 + 9 = 19

🎯 Select all of the ways to make 15.

  • 18 − 3
  • 1 + 14
  • 10 + 5
  • 16 − 1
  • These are ways to make 15:
  • 18 − 3 = 15
    1 + 14 = 15
    10 + 5 = 15
    16 − 1 = 15

🎯 How do you make 14?

  • 0 + 15
  • 16 − 2
  • 9 + 6
  • 0 + 13
  • This is a way to make 14:
  • 16 − 2 = 14
  • These are not ways to make 14:
  • 0 + 15 = 15
    9 + 6 = 15
    0 + 13 = 13

Let’s practice!🖊️