I also used a box of cereal to help introduce inferring. I cover up the box with a piece of cardstock but cut out a little square around part of the name of the cereal, and cut out another little square around part of the picture of the cereal. I discuss with the students how we can use the clues from the text (the name of the cereal), clues from the pictures (in this case the picture of the cereal), and what we already know to figure out what kind of cereal it is. Then I connect this idea to what readers do when they infer with a book.
I'm planning on doing this fun "What's In My Teacher's Bag" lesson from The Inspired Apple on Friday.
Hope this helps!