Example of Value Scales
See attached pic. Use a ruler to draw 2 sets of boxes (between 8-10 boxes each). Use pencil for one row to go from as dark as you can to as light as you can. For the other row, use a colored pencil (not yellow or light pink - they are too hard) to do the same.
You will need to do two scales : one pencil, one colored pencil. 10 boxes, each about an inch wide/long.