The Task

John poured 4/8 out. He had 1/4 left. How much was in the jug before he began? Use the add/subtract box to check your sum.

Teachers' Notes

This task encourages students to use fractions with unlike denominators to find the missing fraction. You could challenge students to ensure that all three fractions have different denominators, or you could choose to allow them to make a fraction with a denominator of 12.

To extend this task, you could ask students to write their own tasks that require fractions with different denominators. You may want to model this using jugs and water in the classroom to help students to visualise the pouring out representing a 'take away' subtraction.

To challenge more able students, Fractions Lab also represents some improper fractions. You could design tasks that ask students to use improper fractions.

You can also read how to subtract fractions with unlike denominators by reading the Quick Start Guide, "Adding and subtracting fractions" and how to check them in "The operations box: compare, add or subtract".