When guests come to the KIPP DuBois Collegiate Academy for a tour, teachers and students want visitors to see the high school just as it is.

So when Tiger Woods made a surprise appearance Tuesday at the school at 12th and Race Streets as part of a meeting his foundation had scheduled with KIPP, what he saw was a typical morning of classes. Well, mostly.

Woods, who was in the area to promote the coming AT&T National tournament in Newtown Square, arrived so unexpectedly that students didn't know he was coming. When Woods visited two classes, KIPP chief executive officer Marc Mannella saw students' jaws drop.

"You saw these beaming smiles," Mannella said. "But they are so focused on their work. When he walked in, there was that look of recognition on their faces, they whispered, then they got right back to their lessons."

KIPP (the Knowledge Is Power Program) operates four grade schools in Philadelphia. The Collegiate Academy focuses on preparing students for college, a mission shared by the Tiger Woods Foundation. The school, which is currently all ninth graders, hopes to team up with the Woods Foundation in the future, possibly on curriculum, Mannella said, as well as funding.

Woods made a last-minute decision to join representatives on the school visit. About 20 minutes before the planned meeting, his reps called with the request.

"They said, 'Tiger wants to know if he can come,' " Mannella said. "If there was ever a no-brainer, this was it!"

Woods showed up shortly thereafter, wearing his golfing clothes, including a Nike hat and shoes. He was treated to a tour by principal Aaron Bass, who let Woods observe physical science and advanced-placement world history classes that were in session.

Woods asked questions about the school and demonstrated extensive knowledge of the programs his foundation is involved in, Mannella said.

"He was totally engaged, which was cool," Mannella said. "He was very businesslike, very professional - but also very easy to talk to."

Within 20 minutes, Woods and his team were gone, on their way to a scheduled news conference in Newtown Square.

"It all happened so fast," Mannella said. "We told the kids, 'Normally we watch what Tiger does. Well, he was so impressed by what you are doing that he wanted to watch you!' "

Contact staff writer Allison Steele at 215-854-2641 or asteele@phillynews.com.