Flip what?

Giving directions in front of the class today, I told my students to turn to the back cover of their books.  One should never assume meaning with 7th graders...I was hoping that common sense would dictate my students to look inside the book for information.  Not one, not two, not three, but 10 students in my first hour class flipped their entire books over to have the back cover facing up...  It's needless to say that I changed the way I gave those directions the rest of the day.