Possible Duplicate:
Printing a book
Is there a method when printing on a5paper with exam class so that it comes out like a book?
Folding down the middle, and have it print the pages in correct order, after you fold it, it follows the pages expected in a book.
examclass) as normal (you probably have to change your paper size to a6paper), and then create another document that puts the pages in the right order etc. -- this is the document whose source is provided in the answer. Another option seems to be thebookletpackage (http://tex.stackexchange.com/a/28779/4012); I haven't checked out how that works. – doncherry Nov 08 '12 at 04:55