Ability to reflect on practice is a key element of early childhood professionalism and is positively associated with the quality of educational services. "Observation-Projet" (Fontaine 2008, 2011b) is a method designed to support practitioners' reflection through the observational process. The method adapts the required scientific procedures to the concrete demands faced by practitioners in their everyday activities. The article presents the results of two projects developed to teach the practitioners the use of "Observation-Projet." The principal aim of Study 1 was to explore how the space was currently used by the children and to intervene on adults' position to enhance children's use of space. In Study 2, the caregivers chose to focus on the organisation of afternoon activities, a time of the day identified as difficult to manage, reducing the number of children per play group and better organising the type of activities offered to children. The results confirm both the intervention efficacy and the "Observation-Projet" effectiveness as an instrument for reflecting and intervening on educational contexts.