Lesson Plan

Students become the Teacher! Flipping Roles to Learn how to Add/Subtract Fractions

Students will understand how to add and subtract fractions with unlike denominators, and create a video demonstrating how to solve these problems.
Jim V.
Classroom teacher
Marshall Elementary School
Wexford, United States
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My Grades K, 1, 2, 3, 4, 5
My Subjects English Language Arts, Math, Science

Students will be able to...

  • Use models to add or subtract fractions with unlike denominators
  • Demonstrate and explain how to use models when adding or subtracting fractions that have different denominators.

Common Core State Standards

  • 5.NF.A.1
    • Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators.
  • 5.NF.A.2
    • Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases of unlike denominators, e.g., by using visual fraction models or equations to represent the problem. Use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers.
Grades 4 – 6
All Notes
Teacher Notes
Student Notes


To introduce the lesson, play the following video from Math Antics.com that focuses on finding the least common denominator: http://mathantics.com/index.php/section/lesson/CommonDenominatorLCD

Be  sure to reinforce the skills taught in the lesson and provide other examples if students need more practice.  After the video is over, tell students that they will be the new "Rob" (Rob is the gentleman who is in the video).  By the end of this lesson, students will be able to create a video lesson that explains how to add and subtract fractions with different denominators.

To assist in student understanding, students will use the Virtual Manipulatives app, which allows students to manipulative fraction bars/strips.  Using the fraction bars will help strengthen connections between equivalent fractions and adding/subtracting unlike fractions.  Use this guiding question to begin a conversation about using fraction bars: How can you use models to add or subtract fractions that have different denominators?


Invite students to share with you what they know about adding or subtracting fractions.  Take a brief step back to review skills.  In a fraction, which part is the numerator?  In a fraction, which part is the denominator?  How do you add or subtract fractions with the same denominator?  Provide examples of adding and subtracting fractions with common denominators to build a foundation.

Bring  students back up to speed by practicing problems together that involve unlike  denominators.  Work through the step by step problems presented in Study Jams: http://studyjams.scholastic.com/studyjams/jams/math/fractions/add-sub-unlike-denom.htm

While working through this problem, introduce students to the fraction bars with the Virtual Manipulatives app.  Guide students through using the fraction bars to solve the problems and finding equivalent fractions.

Here are some other guiding problems for students to practice using the fraction bars.

  • Example: Hilary is making a tote bag for her friend.  She uses 1/2 yard of blue fabric and 1/4 yard of red fabric.  How much fabric does Hilary use?
    • Find 1/2 + 1/4.  Place a 1/2 strip and a 1/4 strip under the 1-whole strip on the virtual manipulative app.
    • Find fraction strips, all with the same denominator, that are equivalent to 1/2 and 1/4 and fit exactly under the sum 1/2 + 1/4.  Record the addends, using like denominators. 
  • Example: Mario fills a hummingbird feeder with 3/4 cup of sugar water on Friday.  On Monday, Mario sees that 1/8 cup of sugar water is left.  How much sugar water did the hummingbirds drink?
    • Find 3/4 – 1/8 .  Place three 1/4 strips under the 1-whole strip on your app.  Then place a 1/8 strip under the 1/4 strips.
    • Find fraction strips, all with the same denominator, that fit exactly under the difference 3/4 – 1/8 . 


For additional practice of adding and subtracting fractions with unlike denominators, students can practice skills using IXL: https://www.ixl.com/math/grade-6/add-and-subtract-fractions-with-unlike-denominators

Once students have a strong understanding of the skill, remind them of Rob's video and how he clearly demonstrated the skill using a video.  Introduce students to the app Explain Everything, including the features and how to record a video.  Allow students time to explore the features and play with the app.

After gaining familiarity, show the problems that students will be required to demonstrate and explain using Explain Everything (feel free to use any problem you choose):

  1. Last week, Jacqueline jogged 1/2 mile on Tuesday, 1/4 mile on Thursday, and 3/8 mile on Sunday.  How far did she jog all last week?
  2. Aaron had 3/8 of a cake left after his party. He wrapped a piece that was 1/4 of the original cake for his best friend. What fractional part did he have left for himself?


During this part of the lesson, allow students to solve the two problems on paper.  Also, remind students to be consciously aware of the steps they are taking to solve the problem as they will need to explain each step in their video.  Depending on your class and students, you may want to pair students together to create the video lesson of the problems.  You can always adjust the difficulty of the problem depending on your students' skills.  I would also recommend that students create an outline of all of the steps needed to solve the problem so they  can  use that when recording  their video.

When students are ready, facilitate and encourage students to be creative with their video.  Students can  add images, fraction bars, or any other graphics into their video.  If students make a mistake while recording, have them edit the video or start a new video.  Remind students that they are the teachers and they have the power!


When students have finished their video lesson, publish the lesson for others to see.  I would suggest sharing the videos through a Google Drive account, posting them to a website (Weebly), sharing them through social media (depending on the size of the file), or posting the lessons on a learning management system (Schoology).

Other ideas:

  • Have other classes or schools in your district view the lessons and provide feedback on the video.
  • Try sharing video with Khan Academy (Maybe Sal will respond to your lesson!)
  • Have students' families view the video and try solving another problem that is related to the video.  Have them evaluate how helpful the video was to their understanding.