MAFS.2.NBT.2.9Archived Standard

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Explain why addition and subtraction strategies work, using place value and the properties of operations.
General Information
Subject Area: Mathematics
Grade: 2
Domain-Subdomain: Number and Operations in Base Ten
Cluster: Level 3: Strategic Thinking & Complex Reasoning
Cluster: Use place value understanding and properties of operations to add and subtract. (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 3: Strategic Thinking & Complex Reasoning - More Information
Date of Last Rating: 02/14
Status: State Board Approved - Archived

Related Courses

This benchmark is part of these courses.
5012040: Mathematics - Grade Two (Specifically in versions: 2014 - 2015, 2015 - 2022, 2022 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 and beyond (current))

Related Access Points

Alternate version of this benchmark for students with significant cognitive disabilities.

Related Resources

Vetted resources educators can use to teach the concepts and skills in this benchmark.

Formative Assessments

Explaining the Standard Algorithm for Subtraction:

Students are asked to explain each step of a subtraction problem completed by using the standard algorithm.

Type: Formative Assessment

Explaining the Standard Algorithm for Addition:

Students are asked to explain each step of an addition problem completed by using the standard algorithm.

Type: Formative Assessment

Using Place Value:

Students are asked to solve a two-digit addition problem using a place value strategy and then are asked to explain why this strategy works.

Type: Formative Assessment

Counting Up To Subtract:

Student are asked to consider why a counting strategy works to solve subtraction problems.

Type: Formative Assessment

Lesson Plans

Subtracting 9 the:

In this lesson, students will use the hundreds chart to discover a strategy to subtract 9 from different numbers. Students will learn and practice the compensation strategy of subtracting 10 and then adding 1 back to get the final difference. Students will also learn and practice visualizing to “mentally see” the hundreds chart and use it as an efficient mental math strategy to subtract 9 from any given two-digit number.

Type: Lesson Plan

Adding 9 the:

In this lesson, students will use the hundreds chart to discover a strategy to add 9 to different numbers. Students will then learn to visualize the hundreds chart as an efficient mental math strategy to add 9 to any given two-digit number.

Type: Lesson Plan

Tutorials

Subtracting with regrouping:

In this tutorial video from Khan Academy, a subtraction problem is solved which contains two numbers each with two-digits. The video demonstrates subtraction with regrouping using the standard algorithm, as well as a method using expanded form.

Type: Tutorial

Subtracting two-digit numbers without regrouping:

In this video tutorial from Khan Academy, explore subtracting two-digit numbers by using the standard algorithm. This video does not include regrouping.

Type: Tutorial

Subtraction by Regrouping:

This 8-minute video demonstrates how to perform subtraction with regrouping. The presenter uses base-10 blocks to explain the rationale and to make a visual connection with the standard algorithm. The examples involve 2-digit and 3-digit numbers.

Type: Tutorial

MFAS Formative Assessments

Counting Up To Subtract:

Student are asked to consider why a counting strategy works to solve subtraction problems.

Explaining the Standard Algorithm for Addition:

Students are asked to explain each step of an addition problem completed by using the standard algorithm.

Explaining the Standard Algorithm for Subtraction:

Students are asked to explain each step of a subtraction problem completed by using the standard algorithm.

Using Place Value:

Students are asked to solve a two-digit addition problem using a place value strategy and then are asked to explain why this strategy works.

Student Resources

Vetted resources students can use to learn the concepts and skills in this benchmark.

Tutorials

Subtracting with regrouping:

In this tutorial video from Khan Academy, a subtraction problem is solved which contains two numbers each with two-digits. The video demonstrates subtraction with regrouping using the standard algorithm, as well as a method using expanded form.

Type: Tutorial

Subtracting two-digit numbers without regrouping:

In this video tutorial from Khan Academy, explore subtracting two-digit numbers by using the standard algorithm. This video does not include regrouping.

Type: Tutorial

Parent Resources

Vetted resources caregivers can use to help students learn the concepts and skills in this benchmark.

Tutorials

Subtracting with regrouping:

In this tutorial video from Khan Academy, a subtraction problem is solved which contains two numbers each with two-digits. The video demonstrates subtraction with regrouping using the standard algorithm, as well as a method using expanded form.

Type: Tutorial

Subtracting two-digit numbers without regrouping:

In this video tutorial from Khan Academy, explore subtracting two-digit numbers by using the standard algorithm. This video does not include regrouping.

Type: Tutorial