Surrealists often depicted other worlds where the impossible could take place. Ask students to study "When Worlds Collide" by Kenny Scharf, 1984; "Prescience" by Roberto Matta, 1939; and "The Storm" by Yves Tanguy, 1926, in which each present a bizarre world where the incongruous is normalised.
Get students to collect disparate imagery and combine them in one larger-scale piece depicting such an alternative universe. Or introduce students to the work of English Pop artist Richard Hamilton. Compare "My Marilyn", which has differing versions of the same image of Marilyn Monroe, with Warhol's pictures of her or those of Jackie Kennedy, as a stimulus for a group project. Give each sixth-former a standard photocopied image of a famous personality, and ask them to imagine that the person's face has been altered by an event in a parallel universe - they must "rework" the image so that it is still recognisable but strangely different. Able pupils might even be asked to combine the common image with one of another famous person so that each is recognisable in their final portrait as in "Portrait of Hugh Gaitskill as a famous Monster of Filmland" by Richard Hamilton, 1964.
Display these in a grid composition alongside the original chosen image as a "Parallel Universe" mural.