Both my Adv. Art and Art 2 classes have weekly sketchbook assignments. Practice, practice, practice! I give them their list of homework assignments in the beginning of the 9 weeks so there are no excuses for not completing assignments. I pick up sketchbooks every Monday with very few exceptions. I try and mix things up a little by asking for sketches that require different mediums, different subject matter or in the manner of (fill in the blank). The majority of the assignments are drawn from life.As the school year progresses I will ask my kids to add layers and writing to their sketches.
My kids are also expected to have their books by them as they work on their pieces. If there is ever a question about a technique, color or composition, it must be resolved in their books. They are also not allowed to start on a piece until they have worked it out in their sketchbooks first.