"Prototypes provide the means for examining design problems and evaluating solutions. Selecting the focus of a prototype is the art of identifying the most important open design questions."

In my experience as a designer, I have always looked at prototyping from a wide scale. This quote suggests looking at a specific problem to prototype for. For example, what the role is of a product and how the product may impact the lives of the user. If the problem is based on how to present the product in a new way, then we can focus on look and feel of prototyping. Lastly if the product is based on a new technique, we can focus on prototyping the implementation the new approach to users.

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"The pizza box was a very efficient prototype. Spending virtually no time building it or considering options, the students got useful feedback on a basic design question—what physical form would be best for the user."

I like the approach to this prototype. It took very little to gain quality insights on how an architect's computer could be used in the field, before even building it. These insights led to an informed direction, opening the ideas of the design team to think about designing the computer like a soft shoulder bag. So far in my design experience, I jump to building a prototype almost to full scale. I need to practice taking a step back and come up with creative ideas that are low in stakes for myself and the user and observe what I can learn in that time of prototyping.

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"...since the prototype was to be shown to a broad audience, an integrated style of prototype was chosen, both to communicate the implementation point and to verify that the piles representation was practically feasible."

With the Pile Metaphor in mind, the implementation of the prototype was meant for a board audience: designers, project managers and developers. What allowed clear communication for the wide audience was the "viewing cone". Hovering the mouse over an icon or "proxy" displayed a short text summary of the document, allowing clear communication between multiple audiences.