When does 1/2 = 1/3? Modelling with wet fractions

Many fraction activities rely on the use of area models for developing partitioning skills. These models, however, are limited in their ability to assist students to visualise a fraction of an object when the whole changes. This article describes a fraction modelling activity that requires the transfer of water from one container to another. The activity provides the opportunity for students to explore the partwhole relationship when the whole changes and respond to and reason about the question: When does ½ = ⅓?