NORWOOD PARK — When Sean Nelson was born Sept. 17, 1999, three weeks early, with a hole in his heart, yellow from jaundice and with Down syndrome, his mother Shannon could think of only one thing.

"My first reaction was, this means he can't go to St. Thecla," she said. "I know that sounds crazy, but it's true."

St. Thecla is a Catholic grade school on Chicago's Northwest Side, but it's been a second home for Shannon Nelson. She graduated from there. Her mom, uncle and four aunts went there, plus a niece and three nephews. Her four other children — Erin, Ryan, Evan and Aidan — all are either alums or attend the parochial school just south of Devon Avenue.

St. Thecla Catholic School eighth-grader Sean Nelson is the first student with Down syndrome in the history of the school, which was founded in 1927. He is scheduled to graduate at the end of this school year, and he has been a St. Thecla student since kindergarten. View Full Caption Shannon Nelson

So sending Sean to St. Thecla was the only option for Nelson and her husband, Jerry, a graduate of rival St. Cornelius School. ("I married him anyway," she said.)

Problem was, St. Thecla, which was founded in 1927, had never enrolled a student with Down syndrome. For the most part, Catholic schools almost never have students with Down's because public schools have far more resources.

"We worked hard to get Sean into St. Thecla," said Nelson, who started asking school administrators when Sean was 2 whether he could become a student there.

When Sean began kindergarten, Nelson coordinated with then-Assistant Principal Margaret Stanton to have Sean spend half his time at St. Thecla and the other at nearby public Onahan Elementary School. Sean's experience at St. Thecla was so positive that by first grade, he was at the school for the whole day.

Sean, who turned 14 on Sept. 17, is an eighth-grader now, in his final year at the school. For his graduation present, he wants a "pink car with no roof."

One of his teachers, Laura Lechner, said a person can't meet Sean and "not feel great about it." Sean is the kind of kid who, on his birthday, "got up in front of the class, told everyone he was having a party, then said it was for girls only and it was a sleepover," Lechner said.

Sean's fourth-grade teacher, Todd Cerjak, said having Sean in his class was "best teaching experience I've ever had."

"You gave him something, but he was able to give you so much more," Cerjak said.

St. Thecla Principal Dan Gargano said he hopes Sean's success and impending graduation lead to more students like him joining the school's ranks. In the last few years, St. Thecla hired a "resource teacher," Megan Schak, who can work with as many as 14 students with special needs. Gargano said he has heard from other parents of Down syndrome children who want to send their kids there.

"Hopefully other Catholic schools will start to model what we're doing here," said Gargano, of Roscoe Village, who said he was extremely pleased and proud that Sean is reading at a fifth-grade level.

Gargano, Cerjak and Lechner stressed that all the students at St. Thecla look out for Sean's best interests. His mother described the school's environment as "a safe place for Sean where he doesn't have to be apologetic."

Nelson's next step is finding a way to place Sean at Notre Dame College Prep in its Burke Scholars Program. According to the school's website, the program is "designed to provide an inclusive Catholic education for young men with mild to moderate cognitive disabilities." Last school year, 19-year-old Ryan Burke became the first student with Down syndrome to graduate from Notre Dame, one of a handful of Catholic high schools in the United States to have such a program.

In his recommendation letter to Notre Dame, Gargano said in part that "Sean has been promoted through each grade level through his own hard work and diligence" and "most importantly, Sean is a student who wants to succeed in all aspects of his life."

For now, Sean said he's "sad" this will be his last few months at St. Thecla.

He has become so attached to the school, he hid in one of its closets two weeks ago.

"I'm going to miss my friends and my teachers. And Mr. Gargano, too, but mostly my friends," Sean said with a smile.