Standard #: MAFS.2.OA.1.a (Archived Standard)


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Determine the unknown whole number in an equation relating four or more whole numbers. For example, determine the unknown number that makes the equation true in the equations 37 + 10 + 10 = ______ + 18, ? – 6 = 13 – 4, and 15 – 9 = 6 + square box.


General Information

Subject Area: Mathematics
Grade: 2
Domain-Subdomain: Operations and Algebraic Thinking
Cluster: Level 2: Basic Application of Skills & Concepts
Cluster: Represent and solve problems involving addition and subtraction. (Major Cluster) -

Clusters should not be sorted from Major to Supporting and then taught in that order. To do so would strip the coherence of the mathematical ideas and miss the opportunity to enhance the major work of the grade with the supporting clusters.

Date Adopted or Revised: 02/14
Content Complexity Rating: Level 2: Basic Application of Skills & Concepts - More Information
Date of Last Rating: 08/14
Status: State Board Approved - Archived

Related Courses

Course Number1111 Course Title222
5012040: Grade Two Mathematics (Specifically in versions: 2014 - 2015, 2015 - 2022, 2022 - 2024, 2024 and beyond (current))
7712030: Access Mathematics Grade 2 (Specifically in versions: 2014 - 2015, 2015 - 2018, 2018 - 2022, 2022 and beyond (current))
5012005: Foundational Skills in Mathematics K-2 (Specifically in versions: 2019 - 2022, 2022 - 2024, 2024 and beyond (current))


Related Resources

Formative Assessments

Name Description
What Number Makes the Equation True?

Students find the missing number in an equation relating four whole numbers.

Relating Four Whole Numbers

Students find the missing number in an equation relating four whole numbers that involves addition and subtraction.

Determine the Missing Addend

Students find the missing addend in an addition equation relating five whole numbers.

Lesson Plans

Name Description
Determine the Unknown in an Equation

Students will apply their understanding of the equal sign as a relational symbol to determine the unknown number in equations relating four whole numbers. Students are encouraged to explore a variety of strategies for equations with addition or subtraction on each side of the equal sign.

The Mystery Of The Missing Number

In this lesson, students will find the “mystery” (missing) number in an addition or subtraction equation relating 4 whole numbers with the unknown in any position. Students will complete an activity in partners, using hint cards as needed.

Into the Unknown

In this lesson, the teacher will introduce using base ten blocks to solve addition equations relating 4 whole numbers with the unknown in any position. Students are given the opportunity to practice with a partner. The students will be engaged with manipulatives, teacher questioning, and partner practice as they determine the unknown number.

Original Student Tutorial

Name Description
Balancing Act

Help Tyler balance equations by finding the unknown number in this interactive tutorial.

Tutorial

Name Description
Understanding the Meaning of the Equal Sign

In this tutorial, you will learn more about what the equals sign means and how to balance equations.

Student Resources

Original Student Tutorial

Name Description
Balancing Act:

Help Tyler balance equations by finding the unknown number in this interactive tutorial.

Tutorial

Name Description
Understanding the Meaning of the Equal Sign:

In this tutorial, you will learn more about what the equals sign means and how to balance equations.



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