Amber Williams doesn't have her driver's license, but she's more than halfway finished with her bachelor's degree.

The college junior turned 16 on Friday, and Charleston Southern University helped her celebrate the milestone birthday with a surprise cake, card and "Happy Birthday" serenade from her classmates and college President Jairy Hunter.

"I was not expecting it at all," she said after Hunter walked in bearing balloons and a gift.

Williams is the youngest student at the private Christian college, and she likely is among the youngest full-time college students in the region. The College of Charleston doesn't have any full-time students under 17, and figures weren't available Friday afternoon for the University of South Carolina or Clemson University.

The only readily available statistics for the state show the number of undergraduates who are younger than 18, but it's not atypical for those with late birthdays to start college at 17.

Williams enrolled as a full-time college student as a 13-year-old, the same year students often begin their freshman year of high school.

Her mother, Tatia Williams, said her youngest daughter always has been advanced. Amber started kindergarten at age 4, and she did her work so fast that she was moved into first grade within a few days.

Amber went on to skip third, fifth and seventh grades. Fourth-grade was her last full year in a traditional school setting, and after that year, Amber was helping high school students with algebra concepts.

Tatia, who teaches second grade at James Island Elementary, began homeschooling Amber in sixth grade, and her mother, also a former teacher, helped with those lessons. Amber did two of her high school years through an online school, and her mother decided it was time for college when Amber became a teenager.

"She was done with all of her high school courses, and she was socially ready," Tatia said.

They picked Charleston Southern University because Tatia graduated from there, and they were familiar with its campus.

Amber said some of her classes are easier than others. She's learned that she's not good at chemistry but has a keen interest in psychology and biology. She's a member of the college's Honors Program and is on the Dean's List with a 3.6 grade point average. She's slated to graduate next spring with a bachelor's degree in psychology, and she likely will start her master's.

"I don't know what I want to do yet (after I graduate)," she said.

Rachel Walker, an associate professor of psychology, taught Amber in a writing and psychology class last semester, and she said Amber was "exceptional." The class was meant to teach students scientific writing, and Amber grasped concepts that many students find to be challenging, Walker said.

"She had the motivation and desire to do well," she said.

Amber said many of her classmates assume that she's 18. Wearing neon-striped Converse shoes and a hoody, and with her fingernails painted green, it's easy to understand why. The petite-framed 16-year-old looks every part the college student.

"I've always been around people a few years older than me," she said. "It feels like it should be weird, but it's not really."

Outside of her sharp mind, she appears to be a typical teen. She loves music, reading and writing fan fiction, and she can't have enough makeup.

"I don't even want to know how much I've spent (in Ulta)," her mother said of the cosmetic store.

Charleston Southern hosted her surprise birthday party during a meeting of the psychology club and psychology honors society, of which Amber is a member. She covered her mouth with her hands in surprise and laughed as they sang her "Happy Birthday."

Hunter asked her birthday wish before she blew out the candles. She said she couldn't say, so he told her to make two wishes - one private and one that she could share with others.

Amber's public wish? "That I do well in my classes."

Reach Diette Courrégé Casey at @Diette on Twitter or (843) 937-5546.

EDITOR's NOTE: A previous version of this story incorrectly identified Williams in the fourth paragraph.