After working on a calculus problem for three hours, Sue took a two-hour break before going back to the problem. She solved the problem soon after she returned to it. Wallas would refer to Sue's two-hour break as a step to problem solving called .

Before they can be published, scientific papers must be peer-reviewed. this means that: a) some other scientific experts read the papers and guarantee that they are true. b) some other scientific experts read the papers and provide quality control by eliminating many mistakes. c) an editor reads the papers, to make sure that all the semicolons are in the correct places. d) everyone in the world is given the opportunity to comment on the papers through a specially maintainedblog. e) government bureaucrats read the papers, to be sure that the papers do not insult the political positions ofthe current officeholders.