Raleigh, N.C. — Wake County public school teachers continue to be at the top of the class when it comes to national certification.

About 22 percent of teachers in the Wake County Public School System hold National Board Certification – more than any other district in the country.

Nationwide, only 3 percent of teachers have obtained certification, which is given to those who meet a rigorous set of professional standards.

Coordinator Carolann Wade says the certification process is about raising the bar in the classroom. Better teachers generally add up to smarter students, she said.

There’s also an incentive: Board-certified teachers get a 12 percent salary supplement.

“That's good for our system and our state because that means we attract more accomplished teachers to stay in our district,” Wade said.

Leigh Ann Alford is one of those teachers. In her fifth year in the classroom, the civics teacher is energized and engaged. Even students give her high marks.

“She simplifies it so it’s interesting to understand and relates it to things that are currently happening,” student Katrina Brown said of Alford’s teaching style.

Alford recently earn national certification and said the lengthy process requires teachers to produce four portfolios of work, videotape classroom instruction and undergo assessments and reviews.

Certification can take up to three years and cost the teacher about $2,500. Only 35 percent of teachers pass the certification on the first try.

“Wake County really puts an emphasis on the fact this can improve teachers' practice,” Alford said.

She said her own approach to teaching has improved since gaining certification, and so has her relationship with students' parents.

“I started a class website that I update daily,” she said. “The parents really like to look.”

Alford cites the district's support and encouragement for certification as one of the reasons she's staying put in the classroom.