Mississippi Math 6.NS.9b

Math6th GradeThe Number System (NS) Apply and Extend Previous Understandings of Multiplication and Division to Divide Fractions by Fractions

The Standard

6.NS.9: Apply and extend previous understandings of addition and subtraction to add and subtract integers; represent addition and subtraction on a horizontal or vertical number line diagram.

Understand p + q as the number located a distance |q| from p, in the positive or negative direction depending on whether q is positive or negative. Show that a number and its opposite have a sum of 0 (are additive inverses). Interpret sums of integers by describing real-world contexts.

2025 Mississippi College- and Career-Readiness Standards for Mathematics · Apply and Extend Previous Understandings of Numbers to the System of Rational Numbers

Teacher's field guide

What This Standard Means

What Students Need to Do: Students start at a number on a number line and move right when adding a positive number or left when adding a negative number. They use the size of the number being added to count the spaces moved. They describe integer sums using situations such as deposits, debts, and temperature changes.
What Mastery Looks Like: A student shows -4 + 6 by starting at -4, moving six spaces right, and landing at 2. They show that -4 + 4 lands at 0 and explain how a debt of $4 and a payment of $4 cancel out.
Common Misconceptions: Some students move left whenever the starting number is negative, even if they are adding a positive number. Others count a negative move as a negative number of spaces, rather than moving left by that many spaces.
How to Assess It: Exit ticket: Draw -3 + 5 and -3 + (-5) on a number line. Write a real-world story for one sum, then explain why 5 + (-5) = 0.

Lesson moves

Ways to Teach It

Tape a number line on the floor; call out -2 + (-4) and have a student start at -2 and walk four spaces left.
Ask students to sketch 6 + (-6) on a number line and write one sentence explaining why it ends at zero.
Give pairs cards showing starting numbers and signed moves; have them draw each sum, compare answers, and correct any mismatched moves.
Show a bank balance of -$8 and a $5 deposit; have students calculate the new balance and mark the change on a number line.

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