Creative thinking:
the wind, sadness, happiness (other emotions represented with symbols, colors, etc.
Collections of objects: toys, books (opened, closed, stacked), kitchen utensils, art materials, contrasting texture items, knick-knack collections, crumpled paper bags, still lifes of fruit or vegetables, clothing hung from hooks or chair backs, assorted balls, a collection of cans from the pantry or shampoo bottles from the shower. Stacks of shoes.  Old hats.  Spools of thread.
Fantasy art: mythological interpretations, invented creatures from actual live creatures, fables and fairy tales.
Story illustrations: for stories they've read or written.  to redo those they don't like, or to emulate or reinterpret those they do like.
Portraiture.  Figures.  Animals.  Transportation forms.  Functional object design, such as the bookbag or windsuit they'd like to have.  "Lautrec of the 90's" poster designs for an event they are involved in.  Formulate an idea and work it out on paper for a new...

I use them for notes, journaling and sketching; also for a short test at the end of our 6 week ( 27day) period; honors art class has weekly sketch assignments.
I have gotten ideas for sketches from the archives. I refine my sketch list each year to keep it interesting. Some ideas:
        - bookmarks for the school library
        - junk food with wrapper
        - part of a vehicle
        - instead of a hand... your foot ( no socks or shoe)
        - something not pretty (one of the 8th grades favoritess)
        - an interior of something (once a student did the inside of a 
           jar of peanut butter)
        - inside of closet
        - 3 unlikely objects together
        - your Mother's or Father's choice
        - part of any object ( mystery draw)
         - a scene that depicts peace

I have used sketchbooks for many years, usually  with grades 7-12.
Here are a few of my favorites:

   * Illustrate your favorite poem
   * Draw the contents of a trash can
   * Drawing of a house plant (real or artificial)
   * Draw an object with a surface texture.
   * Draw tools used in certain professions
   * Draw a tennis shoe
   * draw a grouping of leaves
   * Draw something you might find in a department store display
   * Draw a large jar and fill it up with something (candy, toys, 
      rock, etc)
   * Design a school desk
   * Draw your favorite snack food
   * Draw an object melting
   * Draw a bowl  of fruit, shade it.
   * Draw hands holding something
   * Draw a mechanical object
   * word picture: select a word that bring to mind a mental  picture,
    *Draw the word as the shape of the object. such as the word
      apple in the shape of an apple, or apples spelling out the word.
   * Draw popcorn
   * Keyhole: what would you see through a key hole

In my school, every student in an art class has a sketchbook.  In beginning classes the assignments echo the concepts the students are learning...practicing contour, using different types of line, etc. They have a weekly assignment, as well as keeping track of some in class technical stuff and the writes we do....the studio or advanced kids keep the sketchbooks as process journals...all their class notes, thumbnails, pre assignment work, personal sketching etc goes in them.  The sketchbooks go from art class to art class...they purchase them.  Once in awhile I will find a big sale and resell my incredible bargains to them.  There is paper and tag board or old recycled folders for kids who do not want to pop for the sketchbooks.  The end product is 25% of their grade.  We expect a couple hours of work a week in them. At the end of the semester there are never leftovers in class the kids have a lot of pride in the visible progress they have made.

7th grade was to issue sketchbook packets. These were four to eight pages, photocopied, folded and stapled into a mini-sketch book. Each page had a theme or 'mini-drawing lesson.' 
There was also an area to score each page and a cover page that listed the title of the sketchbook (perspective, cartooning, portraits, etc.) the student's name, total grade, etc. The advantage of these was that the assignment length was short (two weeks) and because we moved on into new themes, the interest level was high. If a kid blew off an entire sketchbook packet, his grade didn't sink him in the class.

I do this type of drawing with high school students, but use a student model.  The students draw with crayons, each person using a different color.  We form a circle around the model and draw until a timer indicates to stop. 
I then instruct them to leave their work and move three chairs to the right.  We draw for another 4-5 minutes, correcting if need be, and continuing the drawing.  I have them move a second time and complete the drawing two spaces to their right.
Each person signs the work, so you can tell by the color who did what.  We critique these, and return each drawing to the person who started it.  It is an excellent drawing method that was given to me in a workshop several years ago.

Just had a great sketchbook experience at the Whitney...about six of us circled a sculpture, did a quick sketch of the object, and then on a signal, laid our sketchbooks on the floor, and moved to the left, to another person's book!  It was rather terrifying, esp. for the totally non-artists in the group.  One woman wanted out...said it was too stressful...another objected to the fact that we could erase and add, and finally, no one left, and we all emerged from the experience with a greater understanding of point of view, and an appreciation of each other's experience...plus, we all have really interesting pencil sketches of a great sculpture by David Smith, c. 1950. This is a great exercise for students, even if you don't have access to a museum (which I don't) but I will prepare a sculpture for them, a la the Styrofoam & dowel hanging sculpture that I got off this list (from SanD, I think, but maybe Alix).

Sketch book Choices and Ideas  
Studio In Art
Mrs. Sumner-Lyman

You need to do at least one sketch per week in your sketch book. This should take between 45- and 60 minutes to do because the purpose of a sketch book is to make you look harder at things, use your imagination, and explore ideas and techniques that interest, challenge, and stimulate you. You will find that practice does indeed pay off and your confidence in your abilities will increase proportionally to the amount of effort and care you put into your work. Full shading is expected, as are details. Use of colored pencils or other materials like pen and ink or your own favorites are fine ! This is your place to experiment and grow ! Remember- you're only limited by your own imagination

SUGGESTED ACTIVITIES

Draw a portrait using light and shadow- place the light from different angles than "normal" -under the chin, behind the head, in front of the face.

Study your feet and shoes. Draw them in different positions and from different angles and views.

Draw studies of your hands. Try a variety of positions or overlapping them.

Draw a figure in an environment from your observation- in motion, and standing still.

Draw in imaginary place- remember to show rich details.

Do a self portrait. This can be full body view or face only. Accuracy !! Gesture drawings of people, things, or animals in motion.

Contour line drawings of figures or objects.

Draw several studies of your eyes, nose, and mouth in a variety of positions and poses.

Focus on drapery and pattern: a shirt over a chair, a sheet around a banister, etc.

Draw everything you can see from where you are positioned: this can be from imagination, like if you were in a hot air balloon, ant sized, etc.

Draw a man made object.

Draw a metallic object and everything you see in it.

Draw or design any kind of vehicle.

Draw an object of interest from 3 different views.

Draw using 2 point perspective.

Draw the inside of a mechanical object.

Filling the page with them, overlap two dimensional forms and pick a direction for the light to hit them from. Shade accordingly.

Draw your reflection in any shiny surfaced object.

Draw a landscape from observation. Remember to show foreground, middle ground, and background.

Draw your home and what's around it.

Draw family members with things that they cherish.

Draw the interior of your room and what's in it- from wherever you're sitting: on floor, up on bed, from ceiling looking down.

Study the forms, shapes, lines and textures and colors of trees.

Draw animals from life ( if you can't see them live, copy them from a reference book.)

Draw a plant with as much detail as possible using line contour and line variation.

Arrange a still life and draw it with shading.

Draw bottles and cans- have the cans crunched up for lots of detail and contrast to the bottles' smoothness.

Draw dishes in a drainer, with shading.

Create a fantasy building and landscape.

Create a series of positive and negative space designs.

Draw a piece of furniture and use color to show the textures and shadows.

Draw a still life with one to three pieces of patterned cloth in it. Show color and patterns.

Focus on textures in a drawing.

MORE SKETCHBOOK CHOICES
(JUST IN CASE YOU NEED MORE INSPIRATION)

Using color (no black) and light (white) create a Impressionist style landscape drawing- remembering to optically mix colors by placing compliments next to each other.

Transform an object from a realistic view to a Cubist representation (using several different view points within the same frame) in a progression of 4 steps.

Draw yourself using a strong light on one side or angle of your face, focusing on the shapes of the shadows of your facial features- excellent shading practice.

Try several studies of DRAPERY- a towel, shirt, or blanket draped around or on another object to create lots of wrinkles; focusing on shapes of folds and creases and the shadows that are created by them.

Advanced drapery- try the same exercise with a patterned cloth in color.

Take out a library book on any artist of your choosing and duplicate their art work. ­Please make a Xerox copy of it for my reference.

Create a series of drawings of people in motion- playing sports; doing housework; etc. Try to overlap several views of the action as it progresses- use light sketchy lines; it will help.

Design a tattoo for someone particular- a celebrity; teacher; etc.

Draw from imagination with s much rich detail as possible- if you were awakened by a crash in the middle of the night; what would it be from ??

Draw yourself 50 years from now; including your surroundings, possessions, etc.

Illustrate a favorite story of yours told by a grandparent; uncle, or other relative.

Design a CD cover for a musical group ( no gangster rap, peace signs; pot leaves, or conventional, unoriginal or violent imagery will be accepted !!)

Draw your greatest fear; your biggest hope; or your dream for your future.

Draw a series of animals in motion.  

More Sketchbook/Drawing Ideas - list from Michal Austin

150 Sketchbook Ideas from Niskayuna Central School. Read through and select ideas appropriate for your students.