Teach How to Subtract Fractions with Unlike Denominators

A flower pot holds four-sixths of a cup of soil. When the pot is moved, two-fifths of a cup of soil falls out.

How much soil is left in the pot?

To work out the answer to this question, your students need to understand that the question involves the subtraction of fractions with unlike denominators. Unlike denominators are fractions that have different denominators, e.g.four-sixths and two-fifths. There are several strategies that students can use when performing these types of operations with fractions. These include:

1. Pictorial models – Pictorial models are diagrams that can be drawn by students to visually represent problems with fractions.
2. Number Lines – Number lines are linear representations of a fraction that can be used to solve subtraction problems.
3. Fraction Notation – With an understanding of fraction notation comes the ability to solve subtraction problems using the standard algorithm.

To help your students better understand these three strategies for subtracting fractions with unlike denominators, the expert teacher team at Teach Starter has created this 30-slide teaching presentation. The presentation explores each strategy in detail using clear and detailed examples of each process. It also includes review activities that the students can work through independently as a means of checking for understanding.

This slide deck downloads in a Google Slides format. Simply project on your screen for a paperless lesson on subtracting fractions with unlike denominators!

Differentiate This Fractions PowerPoint

If you’re looking for ways to differentiate this activity, here are some suggestions from our experienced teacher team:

• Encourage Hands-On Learning – Subtracting fractions is a topic that lends itself extremely well to hands-on learning. When engaging with the presentation, be sure to provide students with physical manipulatives such as fraction strips, blank number lines and mini-whiteboards. These aides will help students to visually represent what can often be a rather abstract concept!
• Write a Word Problem – Have students connect the concept of subtracting fractions to the real world by writing word problems for some of the subtraction equations in the presentation. Students could share these with a partner to solve.

Download to Subtract Fractions with Unlike Denominators

Use the Download button to access the Google Slides version of this resource. (Note: You will be prompted to make a copy of the Google Slides presentation before accessing it.)

This slideshow works best in Presentation mode.

This resource was created by Micahel Collins, a teacher in New York and a Teach Starter collaborator.

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