The project started from the study of Wagenaarstraat Apartment in Amsterdam and Sheats-Goldstein House in Los Angeles during Term 2 Brief 1. The flexible elements in Wagenaarstraat Apartments were concluded and applied to the Sheats-Goldstein House whose original structure was quite solid. Then in Term 2 Brief 2, the definition of flexibility was further discussed which was not limited in structure but extended to light, material and time.