After introducing shelf order, I had students work in groups to put two sets of books in shelf order. One set of books was non-fiction and the other set was either fiction or easy fiction. I did not disclose what type of books were in each set; part of the activity was to figure out what type of books were in each set before putting them in order.
It was very eye opening how difficult some classes, even in the upper grades, found this little activity to be, but I think it helped them better understand how books are put in order in the different sections of the Media Center. I might revisit this activity later in the year just to refresh their memories.
If you're interested, here's a link to the PowerPoint I used to introduced shelf order.