Lesson 16
Dividing Rational Numbers
Lesson Narrative
In this lesson, students complete their work extending all four operations to signed numbers by studying division. They use the relationship between multiplication and division to develop rules for dividing signed numbers. In preparation for the next lesson on negative rates of change, students look at a context, drilling a well, that is modeled by an equation \(y = kx\) where \(k\) is a negative number. This builds on their previous work with proportional relationships.
Learning Goals
Teacher Facing
 Apply multiplication and division of signed numbers to solve problems involving constant speed with direction, and explain (orally) the reasoning.
 Generalize (orally) a method for determining the quotient of two signed numbers.
 Generate a division equation that represents the same relationship as a given multiplication equation with signed numbers.
Student Facing
Let's divide signed numbers.
Learning Targets
Student Facing
 I can divide rational numbers.
CCSS Standards
Glossary Entries

solution to an equation
A solution to an equation is a number that can be used in place of the variable to make the equation true.
For example, 7 is the solution to the equation \(m+1=8\), because it is true that \(7+1=8\). The solution to \(m+1=8\) is not 9, because \(9+1 \ne 8\).
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