The math doesn't add up: schools filled with disadvantaged students struggle to boost achievement.

• Author: Mildenberg, David
• Position: Up Front

Hola abuelo. Puedes darme un chicle, por favor?" Or, "Hello grandpa. Can I have some gum, please?" I hear the Spanish version when I show up to tutor sixth-grade math students at a Charlotte middle school. The grandpa line hurt at first, but I got over it. It's a privilege to work with great kids through the nonprofit Communities in Schools. When I arrive, the class of 20 has just finished lunch. Most bubble with energy. They work in a well-organized classroom with a fancy electronic whiteboard and tablet computers loaded with education software. The teacher, in her second year with Teach for America, is excellent, mixing toughness, enthusiasm and compassion. A teacher assistant helps maintain order. Most of the time, the kids are ready to learn. It's an uplifting scene.

Except it really isn't. Most readers of this magazine would never send their kids to my favorite school. It received an "F" grade in North Carolina's new ranking system covering the 2013-14 school year, based on test scores and how much students improved from the previous year. Various websites rank it in the bottom 10-15% of middle schools, nationally. Hope springs eternal, but I'd be shocked if things changed this year. It's a school packed with the underprivileged and unrepresentative of our state. About half of the students speak limited English, including kids who've come from Mexico, Honduras and El Salvador in the last year. Many don't know their math or division tables. Simple phrases in word problems trip up many kids. At least 85% of the school population gets free or reduced-price lunch, though the school abuts affluent neighborhoods. A friend who lives three...