McCall Middle School student Jack McPadden, 12, won a national Braille contest in Los Angeles late last month. More than 900 children participated in the Braille Challenge, competing in five age categories. McPadden, a straight-A student, earned the top prize in the division for fifth- and sixth-grade students. The annual competition, for blind students in grades 1 to 12, is administered by the Braille Institute of America. Participants must complete four 50-minute tests that measure reading comprehension, speed and accuracy, proofreading, and spelling in Braille, and reading tactile charts and graphs. In addition to some serious bragging rights, McPadden, who lost his sight to cancer as an infant, walked away with a $1,500 cash prize, a Focus 40 Blue Braille Display, which allows him to read and write e-mails independently, and an Apple iPad. “We're so proud of him,’’ said Andrea Bloch, Jack's mother.