Yalies left puzzled by Monday’s New York Times crossword may be surprised to discover that the source of their frustration is one of their classmates, Oliver Hill ’12.

On Monday, Sept. 8, Hill’s puzzle began the New York Times’ first-ever “Teen Puzzlemaker Week.” Starting yesterday and ending Saturday, Sept. 13, the Times’ daily crossword will have been invented by students aged 15 to 19.

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Although Hill, who turned 18 in July, said he enjoyed the few compliments he received for his work yesterday, seeing his name in print is nothing new. Monday’s crossword, after all, was Hill’s fifth contribution to the Times.

Many of his fans, he said, are people he has never met.

“Usually on the days when they come out, I get a number of Facebook messages from random people I never heard of,” Hill said.

Hill’s puzzle will reach both the estimated 1.2 million daily subscribers to the Times and the hundreds of thousands of subscribers to over 30 newspapers that use the Times’ puzzle, including the Oregonian and the Chicago Sun.

All puzzles in the teen series were selected by the Times’ puzzle editor, Will Shortz.

In a phone interview Monday, Shortz said he envisions two purposes for this week: to demonstrate the talents of young puzzle makers and to prove that crosswords are not an outdated form of entertainment.

The Times crossword increases in difficulty throughout the week, so that Monday’s puzzle is the easiest and Saturday’s the hardest.

Although Hill’s puzzle is the easiest, Shortz said that it is in no way simplistic.

“It’s a real fine crossword,” Shortz said. “I don’t think you could tell Oliver’s age from this puzzle.”

Except in one case. Hill showed a bit of his “teen” side in using “Vanessa” — referring to teen actress Vanessa Hudgens — as an answer to a question, Shortz said.

Hill’s father David said he began solving the Times crossword with Hill when the future puzzlemaker was about 13 or 14. According to friends, Hill worked on crosswords whenever he got a chance.

“Oliver was very bored by school,” said Hill’s high-school friend David Hyman. “He’d spend most of class time and out-of-class time working on puzzles. It was obvious that he was concentrating very hard. You could almost call it meditative.”

Hill said he used to make his dad puzzles “as a supplementary item to a birthday gift or whatever.” Hill also created simpler puzzles for his younger sister Charlotte, frequently based around a theme, such as pianos. All this, Hill’s father David said, is just part of his son’s “go-getter personality.”

When Hill found out that Shortz lived just a few blocks away in their hometown of Pleasantville, N.Y., for example, he decided to call up and visit the Times puzzle editor, Hill said. Hill said Shortz was very friendly and supportive and showed him the ropes of crossword construction.

Shortz said he has a more personal relationship with Hill than with most others who make puzzles for the Times.

“He’s my one contributor who’s always dropped off his puzzles in person,” Shortz said.

“Six months [after we met] I brought a puzzle to him, and he gave me the thumbs up,” Hill said. “He said, ‘This one is going to be in the Times.’”

Hill said the puzzle featured in Monday’s paper was that same first puzzle that Shortz approved. After accepting the puzzle, Shortz realized he had already slated another puzzle for that day, and told Hill it would have to wait about a year and a half — until it made its debut in yesterday’s Times.

Students interested in testing their puzzle-solving prowess can try Hill’s puzzle in yesterday’s edition of the Times or online at NYTimes.com/crosswords.