Simplify the following text for a Grade 7 native English-speaking person.
Original: A Rube Goldberg machine , device , or apparatus is a deliberately over-engineered machine that performs a very simple task in a very complex fashion , usually including a chain reaction . The expression is named after American cartoonist and inventor Rube Goldberg .
Simplified: A Rube Goldberg machine is a machine that looks complicated but has a simple function .