Simplify the following text for a Grade 8 native English-speaking person.
Original: Although not a formal proof , a visual demonstration of a mathematical theorem is sometimes called a `` proof without words '' .
Simplified: Proof by contradiction is a way of proving a mathematical theorem by showing that if the statement is false , there is a problem with the logic of the proof . That is , if one of the results of the theorem is assumed to be false , then the proof does not work .