Lesson 1: Fraction Addition and Subtraction

Getting Started

In this unit, you will review fractional numbers, which, like decimal numbers, are used to show partial pieces of whole numbers. You'll also extend your understanding of numbers to include negative numbers and then use all of these numbers to solve problems using a coordinate plane.

You use fractions almost every day, often without even realizing it. Can you think of some examples of situations in which you use partial wholes? Maybe you play basketball for a quarter of an hour before dinner, or perhaps you use 2/3 of a cup of sugar in your favorite muffin recipe. Just like whole numbers and decimals, fractions can be added, subtracted, multiplied, and divided. In this lesson, you will review the basics of fractions as well as the algorithms for adding and subtracting them.

Stuff You Need

  • card stock (kit)
  • glue or glue stick
  • Interactive Notebook
  • scissors

Ideas to Think About

  • Why is it helpful to convert a fraction from one form to another?
  • When would fraction addition and subtraction be used in real-world problem solving?

Things to Know

  • Equivalent fractions have the same value. To make an equivalent fraction, multiply or divide the numerator and denominator by the same number. For example, 9/12 and 3/4 are equivalent fractions.
  • When you simplify a fraction, the fraction will have the smallest possible denominator and numerator. For example, 2/4 simplifies to 1/2.
  • To convert an improper fraction to a mixed number, divide the numerator by the denominator, write the whole number answer, and then write any remainder above the original denominator. For example, 13/3 = 13 ÷ 3 = 4 1/3
  • To convert a mixed number to an improper fraction, multiply the whole number by the denominator, add the numerator to the product of the whole number and the denominator, and then place this number over the original denominator. For example, 3 1/2 = 3 × 2 + 1 = 7/2
  • Easiest common denominator (ECD) method — multiply the denominators together and then convert each fraction to an equivalent fraction. For example, 1/2 and 3/4 (4 × 2 = 8) = 4/8 and 6/8
  • Least common denominator (LCD) method — find the lowest common multiple and then convert each fraction to an equivalent fraction. For example, 1/2 and 3/4 (LCD is 4) = 2/4 and 3/4


  • Apply and extend previous understandings of operations with fractions
  • Solve real-world and mathematical problems involving the four operations with rational numbers

Introducing the Lesson

Your child will begin this unit by reviewing basic fraction information and the algorithms for fraction addition and subtraction. While this information should be review, your child needs a firm understanding of fraction terminology and operations including finding equivalent fractions, converting between improper fractions and mixed numbers, and adding and subtracting fractions and mixed numbers. Your child will use fractions frequently as he moves into higher-level math courses. The following online fraction calculator may prove to be a helpful resource for you as your child works with fractions over the course of this unit.
Web Link