Scaled models offer perspective. Sketches, plans, etc illustrate elements of the design but do not give a complete picture or understanding of how the building works. Scaled models do offer a clear view of how a lot of ideas and elements come together and function (or fail to function) so that the designer might more clearly envision the experiences of the future users. They are a direct form of observation and critique and are useful in the early as well as late stages of the design process. They can illustrate the relationship of materials, the proportions of spaces, the relation to context as well as other attributes including constructive feasibility. The scaled model is a tool and an important one but is one part of the design process and most effective when used in correct conjunction with the other tools.