Introduction

Learn to add and subtract fractions with different denominators by first finding a common denominator. Compare fractions using a range of methods, including converting to a common denominator.

Teaching points

• Teaching point 1: In order to add related fractions, first convert one fraction so that both share the same denominator (a ‘common denominator’).
   
• Teaching point 2: To subtract related fractions, first convert one fraction so that both share a common denominator.
   
• Teaching point 3: The common denominator method can be extended to adding and subtracting non unit related fractions.
   
• Teaching point 4: To add and subtract non-related fractions, the product of the two denominators provides a common denominator.
   
• Teaching point 5: Converting to common denominators is one of several methods that can be used to compare fractions.