Addition strategies

Addition strategies

In this lesson, we will learn:

  • The addition strategies of: (1) using friendly numbers with adjustment, (2) creating friendly numbers using addends, (3) adding on from left to right, and (4) adding by counting on
  • Understanding adding by 9

Notes:

  • Method 1: change into a "friendly" number and then adjust (by subtracting)
    • Round one of the addends to the nearest multiple of 10
    • Then adjust by taking away how much you rounded up by to get the answer
Addition Strategies
  • Method 2: make a "friendly" number using the addends
    • Use the numbers that were given for the addition equation
    • Move values from one number to the other number to make a multiple of 10
Addition Strategies
  • Method 3: adding from left to right
    • Add by going through one place value at a time
    • i.e. hundreds of 1st # + hundreds 2nd # + tens of 1st # + tens of 2nd # + . . .
Addition Strategies
  • Method 4: adding by counting on
    • Start with the first number, then add the second number one place value at a time
Addition Strategies

Lessons

  • Introduction
    Introduction to Addition Strategies:
    a)
    Mental math and sums of 10

    b)
    Addition strategy #1: friendly numbers with adjustment

    c)
    Addition strategy #2: creating friendly numbers using addends

    d)
    Addition strategy #3: adding on from left to right

    e)
    Addition strategy #4: adding by counting on


  • 1.
    Adding by grouping sums of 10
    Add by pairing up sums of 10. Circle the pair and fill in the blanks.
    a)
    8 + 5 + 2 = ____
    10 + ____ = ____

    b)
    1 + 7 + 3 = ____
    10 + ____ = ____

    c)
    6 + 9 + 4 = ____
    10 + ____ = ____


  • 2.
    Adding by 9 strategy
    Add 9 by: adding 10 first, then taking 1 away. Fill in the blanks.
    a)
    7 + 9 = ____
    7 + 10 = ____ - 1 = ____

    b)
    14 + 9 = ____
    14 + 10 = ____ - 1 = ____

    c)
    38 + 9 = ____
    38 + 10 = ____ - 1 = ____


  • 3.
    Adding by 8 strategy
    Add 8 by: adding 10 first, then taking 2 away. Fill in the blanks.
    a)
    7 + 8 = ____
    7 + 10 = ____ - 2 = ____

    b)
    16 + 8 = ____
    16 + 10 = ____ - 2 = ____

    c)
    54 + 8 = ____
    54 + 10 = ____ - 2 = ____


  • 4.
    Adding using friendly numbers with adjustment
    Add by changing one number into a "friendly" number and adjust. Fill in the blanks.
    a)
    Addition Strategies

    b)
    Addition Strategies

    c)
    Addition Strategies


  • 5.
    Adding by making friendly numbers with given addends
    Add: make "friendly" numbers using given addends. Fill in the blank.
    a)
    Addition Strategies

    b)
    Addition Strategies

    c)
    Addition Strategies


  • 6.
    Adding on strategy
    Use the method of adding on from left to right.
    a)
    553 + 385 = ____

    b)
    730 + 291 = _____

    c)
    664 + 148 = ____


  • 7.
    Counting on from the first number
    Add by counting on from the first number
    a)
    104 + 693 = ____

    b)
    827 + 335 = _____

    c)
    568 + 429 = ____