It's early on a Friday morning, and high school chemistry students in Victoria Dawson's class are working equations at the board.
Dawson is peppering the class of 11 girls and four boys with questions, trying to keep everyone focused as she helps correct mistakes.
When a student gets one of the dense equations right, Dawson and the class salute with finger-snapping in place of applause
"I want some A's on Tuesday," the teacher says, warning of an upcoming test.
In a state where Republican leaders are trying to put their stamp on long-running efforts to improve education, Clarksdale is emblematic of both the challenges the state faces and innovative ideas for boosting schools. Dawson's class is part of a program in the district to develop a more rigorous high-school curriculum.