BOSTON — Alanna Clark still remembers the stress of third-grade reading time. When her class read books together aloud, Alanna would often become confused. She didn’t understand how her classmates could answer the teacher’s questions about the book so quickly. As they did, Alanna was still just trying to take in the words.

“It was frustrating, because I used to think, maybe I’m reading the wrong part,” she said. “But I wasn’t.”

Alanna had a reading disability, and she was falling behind. Her mother repeatedly asked the school for help, without success — and then began to fear that a pattern was repeating itself. Alanna’s sister, who was 12 years older, had also struggled in school. But schools kept promoting her, until she eventually made it to community college, where, unprepared, she flunked.

With this fear as a spur, Alanna’s mother entered her into the long-shot lotteries that allow Boston children to attend schools outside their neighborhood. Alanna won one of them, and today is a poised, soft-spoken 10th grader at a charter school called Match, housed in an old auto-parts store on Commonwealth Avenue.