The Task

Kiri was subtracting fractions but forgot how she made the solution 5/4 using two jugs. Show a subtraction she might have made, using two fractions with the same denominator.

Teachers' Notes

This is a problem solving task that encourages students to think about different possibilities. You could encourage students to think about the patterns they might identify to help them find some of the possible solutions. You could also ask them to make some of the possible solutions on Fractions Lab and consider how the patterns look on the screen. Taking a screenshot and discussing it away from the screen could lead to other opportunities such as displays or group discussions.

This task uses improper fractions. You may wish to design further tasks where improper fractions are used. Fractions Lab will create fractions up to the equivalent of 3/1, e.g. 6/2, 9/3, 15/5.

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