This paper proposes a Situation Design that designs not only the experience of behavior itself, but also the experience of the environment around the behavior. The research question of this paper is how to motivate children to paint. To find answers, we implemented an iPhone application. The app we came up with was The World Is Canvas; using it, one will be able to enjoy coloring based on a Situation Design. We adopted physical interaction, the function of which is to paint on the screen with fingers, as a design of a painting experience itself. We also adopted social interaction as a design of the environment around behavior, with the goal of offering fun. For social interaction, we adopted a mobile device with a network connection and a function to generate a draft for coloring by using a photo taken by the user. We conducted user evaluation tests on 111 children to analyze their user experience, and we demonstrated that they enjoyed themselves through these approaches.