When I assign a sketchbook drawing they are worth 50 points (middle school and high school). I will give full credit for the drawing IF it is obvious the student put forth effort. I also make a point to the students that their sketchbooks are personal - I am the only one that is going to look at them when they are in my posession. If a student chooses to share that is up to them, but I will not show anyone else what is in their books. I think this trust factor helps a majority of my students helps them to at least try to achieve quality results. By doing the rotation of observation, imagination, article review the students all have at least one week they enjoy and can be completely successful.
K-12 Art Teacher
I pick up the books for grading every 3 weeks and grade on quantity and relavance to the theme (basically- following directions). Grading is very objective at this point . My sketchbooks are worth 30 % of their final grade.
Hope this helps a little...
Kathy in Kalamazoo ---