Inspired by Composition No.10 of Piet Mondrian, the system is to develop an improvisational pattern out of rigidity. The Impromptu project is Designed for a multi-generational family of 4 members, to explore the versatility and possibility in circulations and material.The planar circulations help create needed privacy or interaction in different scenarios; the vertical circulation of kitchen,dinning and living area creates change of conversation; the variation of material embodies the concept of improvisation.