Here is how you have to think to create a crossword puzzle that gets published in the Sunday New York Times Magazine.

Georgia State University College of Law professor Sam Donaldson was getting on an airplane some time ago and looked at the boarding pass in his hand. The phrase “fly paper” came to his mind.

Donaldson, who teaches taxes and estates, later contacted Doug Peterson, a California friend who's collaborated with Donaldson on previous puzzles. They came up with a list of nine other clues, such as “scratch paper,” “wax paper” and “term paper.” They stood for the phrases—spoiler alert!—”lottery ticket,” “record deal” and “contract.”

From there they went to a software program that helps create a puzzle following strict rules set by the Times' puzzle editor in the 1940s. On May 5, their opus “Paper Work” anchored the Times Magazine's puzzles section, which hundreds of thousands of readers devour each week.

“It's one of the few meritocracies left,” Donaldson says of how the pair's puzzle got the OK from the newspaper's famed puzzle editor, Will Shortz.

Donaldson said the Times receives about 125 daily crossword submissions each week and chooses, of course, only seven to be published. In the past 11 years, Donaldson has created or co-created 32 that made the Times' grade and others that were published elsewhere.

Donaldson was introduced to crossword puzzles growing up in Portland, Oregon, sitting with his father while he worked puzzles from both the morning and evening newspapers.

In 2006, Donaldson said his interest in puzzles went to a new level when he saw the documentary “Wordplay,” which is about Shortz and his loyal fan base. Two years later, Donaldson went to a national crossword contest. “I did horribly but had the best weekend,” he said.

He met a host of puzzle creators, whom he credits with generously offering suggestions and feedback on his first efforts to create puzzles.

The Times pays between $500 and $2,250 for puzzles, depending on when they run during the week and how frequently a contributor's work has been published. Donaldson sounds happy to keep his day job teaching law, even as he faces a stack of final exams on his desk. He jokes that he teaches law for free, and “They pay me to grade.”

Donaldson says he does not deliberately drop law-related clues and answers into puzzles because they need to appeal to a wide audience. However, the Times published a puzzle by Donaldson and co-creator Patrick Blindauer on Tax Day, April 15, in which five answers included varying forms of “IRS.”

When a reporter suggests if this week's Sunday puzzle focusing on paper could have included the clue “paper chase,” referring to the movie about a law professor, Donaldson shakes his head.

All of Sunday's clues related to the theme used the word “paper” second, such as “crepe paper,” so the Times' editors would have dinged “paper chase” as inconsistent.

“It has to be airtight,” Donaldson says.

He explains that Times' puzzles get progressively harder from Monday through Saturday, with the Sunday puzzle expected to be at a Wednesday or Thursday level. So, if he were writing for a Monday puzzle, the clue for “salt” might be “pepper partner,” while a Thursday clue might be “ocean inhabitant.”

Donaldson doesn't mind if solvers use the internet to look up answers to some clues, referring to Shortz's refrain, “It's your crossword,” so readers can do whatever they want.

Donaldson sounded proudest of a 2009 puzzle in which all of the answers along the border were made of words like “malaria” and “Gandhi” that included two-letter state abbreviations. The theme was revealed in an answer in the middle, “twenty six states.”

Donaldson said he hears from many Times' solvers. A common complaint is when a clue is particularly hard. “If it's something they didn't know,” he says, “it's 'obscure.'”