The next time your teacher scolds you for "zoning out," refer him to this study by psychologists Benjamin Baird and Jonathan Schooler at the University of California Santa Barbara:
History is rich with 'eureka' moments: scientists from Archimedes to Isaac Newton and Albert Einstein are said to have had flashes of inspiration while thinking about other things. But the mechanisms behind this psychological phenomenon have remained unclear. A study now suggests that simply taking a break does not bring on inspiration — rather, creativity is fostered by tasks that allow the mind to wander. [...]
As well as revealing that breaks on their own do not encourage creative thinking, Baird’s work suggests an explanation for one of psychology’s great mysteries: why we zone out.
From an evolutionary perspective, mind-wandering seems totally counterproductive and has been viewed as dysfunctional because it compromises people’s performance in physical activities. However, Baird’s work shows that allowing the brain to enter this state when it is considering complex problems can have real benefits. Zoning out may have aided humans when survival depended on creative solutions.