Object Orientation, in easy words …

Hi,

As a teacher I want to give a lesson on the principles of object orientation, as this is the way information systems are built nowadays. However, all the white papers I found are far to complex, too large for an 18-year-old public of sporters, interested in IT.

How can give me advice where I can find a short (a few pages), easy explication of what OO is. If possible with graphics.