I start sketchbooks with grade 2 up. We use them to sketch ideas for
sculptures, paintings, for doing self-assessments (whatever form they take),
the occassional free draw, etc. If we do any reading I have the students
staple a copy in the sketchbook. It ends up being a nice record of
preliminary work, especially for the older students. It can give parents a
real view of their child's creative process.