sentence: Fans are used when it's very hot.
sentences_before: A 'fan' is a device that people use for cooling themselves down. To cool yourself down with a handheld fan, you must wave the fan up and down near your face.
sentences_after: People also use electric fans and air conditioners to make cooling themselves easier since they don't have to do all the hard work. Fans can also be on a ceiling or in the ground.
concept_name: fan
headings: Fan
categories: Machines