I've read all sorts of blogs with great Montessori sorting activities. This was my first attempt.
I cut a bunch of straws in several different colors. I then got out an ice cube tray and put one color in each little cube. I thought my daughter would jump right in a start sorting. Not quite. After feeding the straw pieces to her dragon, putting them between her toes, and trying to throw them at her brother, she then decided to try putting them in the ice cube tray, but moved on quickly seeming pretty uninterested. Even though she wasn't interested in sorting, I enjoy watching her discover a new material through play.