There is growing consensus internationally that creative thinking is important (e.g., Care et al., 2012; Kereluik et al., 2013). Beyond identifying the importance of creativity, however, there is little consensus on how to develop and teach it (and even whether this is necessary), due in part to a lack of clarity or even agreement about the nature of creativity as a skill (Simonton, 2012), including what constitutes its fundamental building blocks and how it develops and changes in a learner. This is where assessment can help. Specifically, formative assessments that can identify what a learner can do in relation to a skill, and what they need to know or be able to do to progress further, can inform teacher instruction and support students to progress towards mastery (Lucas, 2016).