Simplify the following text for a Grade 10 native English-speaking person.
Original: Terry Pratchett 's Strata and Discworld novels ( 1983 onwards ) are set on a flat , disc-shaped world resting on the backs of four huge elephants which are in turn standing on the back of an enormous turtle .
Simplified: Terry Pratchett 's Discworld novels ( 1983 onwards ) are set on a flat , disc-shaped world that rests on the backs of four huge elephants that stand on the back of an enormous turtle .