Lesson 2

Using Common Denominators

Est. Class Sessions: 2–3
X

Mathematical Standards

5.NF.A
Use equivalent fractions as a strategy to add and subtract fractions. (5.NF.A.1, 5.NF.A.2)
5.NF.B
Apply and extend previous understandings of multiplication and division. (5.NF.B.4, 5.NF.B.6)

Standards for Mathematical Practice

MP1.
Make sense of problems and persevere in solving them.
MP2.
Reason quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP4.
Model with mathematics.
MP5.
Use appropriate tools strategically.
MP6.
Attend to precision.
MP7.
Look for and make use of structure.
MP8.
Look for and express regularity in repeated reasoning.

Students find common denominators and use them to add, subtract, and compare fractions. They use estimation to check the reasonableness of their answers.

Content in this Lesson

  • Identifying and finding equivalent fractions using fraction circle pieces, number lines, and multiplication and division strategies [E1, MPE2].
  • Finding common denominators and using them to add, subtract, and compare fractions [E10, MPE2].
  • Adding and subtracting fractions including those with unlike denominators using area models and paper-and-pencil methods [E8, MPE2].
  • Making connections between fraction circle pieces and paper-and-pencil methods for adding, subtracting, and comparing fractions.
  • Estimating sums and differences of fractions using benchmarks and mental math strategies and checking for reasonableness [E9, MPE3].
  • Solving word problems involving addition and subtraction of fractions [E5, MPE1].
  • Representing addition and subtraction of fractions with fraction circle pieces, number lines, and number sentences [E2].
  • Explaining solution strategies [MPE5].
  • Using labels to show what numbers mean [MPE6].

Daily Practice and Problems E–H

E. Division

F. Factor Trees

G. Find the Unknown

H. Operations

X

Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Guide

Teacher Resources

 Teacher Guide - digital

Supplies for Students

  • fraction circle pieces

Materials for the Teacher

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed

Using Common Denominators
Check-In: Question 13
Student Guide
Page 464
and corresponding
Feedback Box
Teacher Guide - digital
E1.
Identify and find equivalent fractions using tools (e.g., area models, number lines) and multiplication and division strategies.
E3.
Represent addition, subtraction, multiplication, and division of fractions with area models, number lines, number sentences, drawings, and stories.
E5.
Solve word problems involving addition, subtraction, and multiplication of fractions.
E8.
Add and subtract fractions including those with unlike denominators using area models and paper-and-pencil methods.
E9.
Estimate sums and differences of fractions using benchmarks and mental math strategies.
E10.
Find common denominators and use them to add, subtract, and compare fractions.
MPE1.
Know the problem. I read the problem carefully. I know the questions to answer and what information is important.
MPE2.
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE3.
Check for reasonablness. I look back at my solution to see if my answer makes sense. If it does not, I try again.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
MPE6.
Use labels. I use labels to show what numbers mean.

Working with Fractions Quiz
with Feedback Box
Teacher Guide - digital
E1.
Identify and find equivalent fractions using tools (e.g., area models, number lines) and multiplication and division strategies.
E5.
Solve word problems involving addition, subtraction, and multiplication of fractions.
E8.
Add and subtract fractions including those with unlike denominators using area models and paper-and-pencil methods.
E9.
Estimate sums and differences of fractions using benchmarks and mental math strategies.
E10.
Find common denominators and use them to add, subtract, and compare fractions.
MPE1.
Know the problem. I read the problem carefully. I know the questions to answer and what information is important.
MPE2.
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE3.
Check for reasonablness. I look back at my solution to see if my answer makes sense. If it does not, I try again.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
MPE6.
Use labels. I use labels to show what numbers mean.