Scenario:
A student sets down at the desk. Slides the note book sideways and flips up the cover to function as a screen. Sets the phone down and opens it up.
The image is projected on the screen, the keyboard is projected on the desk.
At the end of class, the student puts the phone back in the pocket and moves on to the next class.
If this takes place, students bring the technology with them. No need for computer labs, infrastructure, data storage, or a building tech.

How:
Camera with a built in projector for viewing a larger screen:
http://www.textually.org/picturephoning/archives/2006/04/012048.htm Light emitted keyboard:
http://www.alpern.org/weblog/stories/2003/01/09/projectionKeyboards.html We certainly teach in exciting Tech-know-Times.
