Operations with Rational Numbers

Lesson 13

Math

Unit 2

7th Grade

Lesson 13 of 18

Objective


Multiply signed rational numbers and interpret products in real-world contexts.

Common Core Standards


Core Standards

  • 7.NS.A.2.A — Understand that multiplication is extended from fractions to rational numbers by requiring that operations continue to satisfy the properties of operations, particularly the distributive property, leading to products such as (-1)(-1) = 1 and the rules for multiplying signed numbers. Interpret products of rational numbers by describing real-world contexts.
  • 7.NS.A.2.C — Apply properties of operations as strategies to multiply and divide rational numbers.

Criteria for Success


  1. Apply the rules of multiplying signed numbers to find the products of rational numbers.
  2. Given a product, find factors that multiply to get the product.
  3. Write multiplication problems with signed rational numbers to represent contexts.

Tips for Teachers


Continue building fluency with mental math and other activities.

Fishtank Plus

Unlock features to optimize your prep time, plan engaging lessons, and monitor student progress.

Anchor Problems

25-30 minutes


Problem 1

Your dog’s veterinarian recommends that you put your dog on a diet to lose some weight. You change your dog’s food and feeding schedule and keep a log of his weight. On average, you notice that your dog’s weight changes by $$-0.8$$ pounds per month. Write an expression to represent the total change in your dog's weight after $$6$$ months. What number represents the change in your dog’s weight?

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem 2

List three factors that have a product of $${-{3\over5}}$$? Can you think of another set of three factors? 

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem 3

On the number line below, $${|a| < |b|}$$. Which expressions are negative? Select all that apply.

 

A.   $${ab}$$

B.     $$-({ab})$$

C.     $${(-a)(-b)}$$

D.      $${2a}$$

E.   $${2b-a}$$

F.     $${2a}-b$$

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem Set

15-20 minutes


Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.

Target Task

5-10 minutes


Problem 1

On Thursday, the temperature was 64 ℉. Since Monday, three days earlier, the temperature had decreased consistently by 2 degrees each day. What multiplication expression represents the change in temperature from Thursday to Monday? Explain what each factor in your expression represents.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem 2

Find the product:

$${1{1\over2} \times \left( -{7\over8} \right )}$$

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem 3

Determine if the statement is always, sometimes, or never true: The product of any two numbers is the product of their opposites.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Additional Practice


The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

  • Include procedural practice multiplying signed rational numbers, including integers, fractions, and decimals
  • Include problems with real-world contexts or have students write contexts to represent multiplication problems.
  • Include problems where students identify equivalent expressions.

Next

Determine the rules for dividing signed numbers.

Lesson 14
icon/arrow/right/large

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Adding and Subtracting Rational Numbers

Topic B: Multiplying and Dividing Rational Numbers

Topic C: Using all Four Operations with Rational Numbers

Request a Demo

See all of the features of Fishtank in action and begin the conversation about adoption.

Learn more about Fishtank Learning School Adoption.

Contact Information

School Information

What courses are you interested in?

ELA

Math

Are you interested in onboarding professional learning for your teachers and instructional leaders?

Yes

No

Any other information you would like to provide about your school?

We Handle Materials So You Can Focus on Students

We Handle Materials So You Can Focus on Students

We've got you covered with rigorous, relevant, and adaptable math lesson plans for free