Simplify the following text for a Grade 12 native English-speaking person.
Original: The Foucault pendulum , or Foucault 's pendulum , named after the French physicist LÃ on Foucault , is a simple device conceived as an experiment to demonstrate the rotation of the Earth .
Simplified: The Foucault pendulum , or Foucault 's pendulum ( named after the French physicist LÃ on Foucault ) was created as an experiment to show the rotation of the Earth .