Though perspective is an illusion used by many artists to convey a sense of three-dimensional space, some have centred their work solely on optical illusions. For example in "Island No. 10" Frank Stella plays with perceptual geometrical effects to confuse the eye. Accustomed as the viewer is to seeing images three-dimensionally, a flat pattern of squares inside squares seems to move forward or backwards. Other artists, such as Victor Vasarely, became known as "OP" artists because of their aggressive optical patterns which assault the viewer.
Using cut paper squares and circles in a checkerboard formation start with simple black-and-white optical repeating patterns. A wide range of examples, from simple to highly complicated, can be found in Visual Elements; Marks and Patterns (Columbus Books) and Japanese Optical and Geometrical Art (Dover Books). Photocopy examples so that pupils can cut them up, combine or rearrange them into new designs.
Surrealist works by Magritte ("The Promenades of Euclid", 1955; "The Domain of Arnem", 1962) present visual illusion and paradox, which fascinate pupils. Seemingly impossible visions feature in works such as Gustave Moreau's "The Apparition - Dance of Salome" (1876) or Escher's visual conundrums. Introduce "impossible visions" by giving pupils black-and-white photocopies of landscape photographs.
For homework, ask pupils to introduce "a visionary image" or a contradictory element in an incorrect scale by adding collaged pieces from a magazine. Re-photocopy to produce a consistent black-and-white image in larger format, the subtle effect of Whymper's woodcut being simulated by drawing with a ball-point pen on to Quickprint (a dense polystyrene sheet), producing a line drawing to print from.