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Operations and Algebraic Thinking: Finding the Unknown Number CCSS 1.OA.8 Facts & Worksheets

Similar to finding the unknown addend, generally, finding an unknown number in an equation means relating a set of numbers in a fact family.

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Worksheets /Math /Grade 1 (ages 6-7) /Operations and Algebraic Thinking: Finding the Unknown Number CCSS 1.OA.8 Facts & Worksheets

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Operations and Algebraic Thinking Finding the Unknown Number CCSS 1.OA.8 Worksheets
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Similar to finding the unknown addend, generally, finding an unknown number in an equation means relating a set of numbers in a fact family.

See the fact file below for more information on the finding an unknown number or alternatively, you can download our 26-page Operations and Algebraic Thinking: Finding the Unknown Number CCSS 1.OA.8 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 determine the whole unknown number in an addition or subtraction equation relating three whole numbers.

A NOTE FOR THE TEACHER

  • When finding the unknown number, take note of the following:
    • Remember that if the missing number is the sum/difference, do the necessary operation. If the missing number is an addend, subtract the addend from the sum. If the missing number is a subtrahend, subtract the difference from the minuend. If the missing number is a minuend, add the difference and the subtrahend.

THEORY

  • Similar to finding the unknown addend, generally, finding an unknown number in an equation means relating a set of numbers in a fact family.
  • If the missing number is the sum or difference, do the necessary operation.
  • For example,
    • 12 + 2 = ?
    • Adding 2 to 12 will produce 14
    • Thus, 12 + 2 = 14
    • 14 – 3 = ?
    • Subtracting 3 from 14 will produce 11
    • Thus, 14 – 3 = 11
  • If the missing number is an addend, subtract the other addend from the sum.
  • For example,
    • 13 + ? = 15
    • Subtracting 13 from 15 will produce 2Thus, 13 + 2 = 15
  • If the missing number is a subtrahend, subtract the difference from the minuend.
  • For example,
    • 16 – ? = 12
    • Subtracting 12 from 16 will produce 4
    • Thus, 16 – 4 = 12
  • If the missing number is a minuend, add the subtrahend and difference.
  • For example,
    • ? – 5 = 12
    • Adding 5 to 12 will produce 17
    • Thus, 17 – 5 = 12

Operations and Algebraic Thinking: Finding the Unknown Number CCSS 1.OA.8 Worksheets

This is a fantastic bundle that includes everything you need to know about Operations and Algebraic Thinking: Finding the Unknown Number across 26 in-depth pages. These are ready-to-use worksheets that align with the Common Core CCSS code 1.OA.8 for Operations and Algebraic Thinking: Finding the Unknown Number.

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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