This study explored the role of assessment to effectively facilitate curriculum reform aiming to foster children's creativity and teachers' creativity fostering behaviours (CFB). A "flipped-measure" was introduced by deliberately positioning a mode of formative assessment in the centre of the curriculum modifications, rather than after modifications. Children's creativity was measured using the Preschoolers' Creativity Test and teachers' CFB was measured with the Creativity Fostering Teacher Behaviour Index (CFTIndex) at three-time intervals during one academic year. Results showed that the newly-adopted child-centred curriculum and pedagogy, which was launched concurrently with a formative assessment, significantly enhanced children's creativity (p < .001) and teachers' CFB (p = .001). The findings suggested that the mode of an assessment scheme, "re-positioning" of formative assessment and curriculum modifications, all play important roles in leading a curriculum reform geared towards promoting children's creativity and teachers' CFB.