Provide some value-add over real-world counterparts
The initial value of RealThings lies in ease of use resulting from recognition and intuitive operation. But in many cases the computer should allow us to do things better than we can in the real world. Look for opportunities to provide additional value. Provide some function that isn't possible or practical in real world counterparts.
For example, the RealPhone allows users to dial alphanumeric phone numbers
like 1-800-CALL IBM by typing the letters. The user doesn't have to convert
the letters to the proper digits on the number pad. This is a simple example
and much more powerful assistance should be practical.
When providing value-add over the real-world make sure that the user's model is in no way distorted or, worse still, broken.