Two dozen or so Oceanside Charter School students have been staying an hour late almost every day since getting back from their holiday break to prepare for the school’s 13th annual Winter Festival next week.

The event at the Atlantic City school always is meant to be fun, but perhaps more so this year, given its carnival theme. The faculty-run games and activities will stress mathematical concepts such as building numbers by creating Mardi Gras-style costume masks adorned with fluorescent digits that add up to a certain total. Oceanside’s Math League will demo the myriad computer games that have become such serious competition among the numbers-obsessed that those students thinking

The school will run multiple raffles — prizes include multiple flat-screen TVs, one limited to those who bring someone who isn’t enrolled, but interested in going to Oceanside, vice principal John Newsome said.

“People might have heard about the school through word of mouth, but to be able to check out what we do in terms of programs and what we offer, that’s a different experience for them,” said Wesley Mayo, advisor for the school’s Art Club. “They actually get to come and see what we do, and they can take home folders on our school, our programs. It’s a little more formal in a way.”

The students don’t have to come, but nearly all of them do each year. And attendance almost always totals at least 500, or about 50 percent more than the student body, Newsome said.

Mayo’s Art Club carefully painted white T-shirts with neon colors last week. The 2013 winter festival is focused on math, so the only instruction for the shirts is to stick to that theme. Each of them picked different numbers, for different reasons. Dramond Reese, 12, of Pleasantville, for example, painted the number eight in the center of her shirt, larger than any of the other tiny digits scattered on the rest of the garment because, she said, “that was a good year.” Her friend Kayci Kelly, 11, of Atlantic City picked 12 because her birthday is Feb. 12 — like Abraham Lincoln, Kelly said.

Regardless of the motivation for their numerical selections, all of them took care to pick the colors with the most phosphor because those will “pop” during their blacklight presentation that will conclude Thursday night’s festivities, said 14-year-old Dion Alexander, of Atlantic City.

As Alexander, Kelly, Reese and other sixth-through-eighth graders crafted their T-shirts alongside Mayo, another group played Internet-based computer games meant to hone math skills. Multiple websites offer dozens of games that can be tailored to stress different concepts at different levels, and generate reports that instructors and parents can review privately to identify each child’s strengths and weaknesses, said math teach Quenna Martin, also the league’s coach.

Anyone who comes to Thursday’s fest can try the games, which will be demonstrated by Martin’s students during the evening leading up to a fundraising presentation revealing results of their ongoing coin collection drive to benefit St. Jude’s Children Hospital in Philadelphia.

“Some of the students really like it. It can get really competitive,” said Martin, who rewards score leaders at the end of each week with Jolly Ranchers and extra credit to support their grades.

It wasn’t just candy, but also bragging rights that hooked Daisha Caldwell, 13, of Pleasantville, to the point that she logged extra sessions during her free time to get ahead.

“Everybody was just saying, ‘Oh, I got a chimpanzee!’ And I thought, I want a chimpanzee. So I came after school, on the weekend, and I got a polar bear,” said Caldwell, referring to the progressive point-system that corresponds to different animals in the game Arcademics.

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