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Operations and Algebraic Thinking: Addition and Subtraction within 20 CCSS 1.OA.6 Facts & Worksheets

There are different ways to add and subtract within 20. Take note that we are handling up to two-digit numbers, so we are handle the one’s place and the tens place.

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Operations and Algebraic Thinking Addition and Subtraction within 20 CCSS 1.OA.6 Worksheets
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There are different ways to add and subtract within 20. Take note that we are handling up to two-digit numbers, so we are handle the one’s place and the tens place.

See the fact file below for more information on the addition and subtraction within 20 or alternatively, you can download our 26-page Operations and Algebraic Thinking: Addition and Subtraction within 20 CCSS 1.OA.6 worksheet pack to utilise within the classroom or home environment.

Key Facts & Information

LEARNING OBJECTIVE

  • At the end of the lesson, the student will be able to add and subtract within 20 using strategies like counting on, making 10, decomposing a number leading to a ten, using the relationship between addition and subtraction, and creating equivalent sums.

A NOTE FOR THE TEACHER

  • When adding and subtracting within 20, take note of the following:
    • Remember that you are dealing with two place values: ones place and tens place
    • Decomposing a number means knowing what two numbers add up to produce the number to be decomposed
    • Memorize the known sums like 5+5=10 or 6+6=12

THEORY

  • There are different ways to add and subtract within 20.
  • Take note that we are handling up to two-digit numbers, so we are handle the one’s place and the tens place.
  • Counting on
    • From the starting number, count 1 value higher or lower until you end with the number of times you need to count on.
  • Making 10
    • Identify pairs that add up to 10 before adding the whole equation.
    • For example, 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14.
  • Decomposing a number leading to a 10Identify a subtrahend that can lead to an answer of 10 before subtracting the whole equation.
    • For example, 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9.
  • Using the relationship between addition and subtraction
    • Fact families prove that an addition equation can have the same set of numbers in subtraction.
    • For example, the number 4, 8, 12 can have equations of
    • 4 + 8 = 12 8 + 4 = 12        12 – 4 = 8        12 – 8 = 4
    • Thus, if 4 + 8 = 12, then 12 – 8 = 4.
  • Creating equivalent but easier or known sums
    • Memorize known sums to decompose an equation easier.
    • For example, adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13

Operations and Algebraic Thinking: Addition and Subtraction within 20 CCSS 1.OA.6 Worksheets

This is a fantastic bundle that includes everything you need to know about Operations and Algebraic Thinking: Addition and Subtraction within 20 across 26 in-depth pages. These are ready-to-use worksheets that align with the Common Core CCSS code 1.OA.6 for Operations and Algebraic Thinking: Addition and Subtraction within 20.

Table of contents:

  • A lesson plan
  • Warm-up activity
  • Math theory explained
  • Assisted learning activities
  • Independent learning activities
  • Extension activities and games
  • Answer keys

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Use With Any Curriculum

These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.

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