I have a student now that due to several reasons cannot read or write.  I only have the student for two subjects and during our time with those subjects the student puts his finger on the page as if he is following along, but has no clue where the class is.  The student is constantly cutting papers and never doing the assignment like the rest of the class.  The student does not even remember my name, but if I give this student a verbal test the student receives grades of 80%.  I have no idea how he is retaining the information when he is talking and looking at a completely different page, cannot remember my name, but can get almost every answer correct.  Clearly he is able to concentrate on what is being read or spoken to him in those environments even though according to my eyes he's not paying attention at all.  Just reminded me an example of multi-processing.