Scratch: Programming for All. - RESNICK, MITCHEL; MALONEY, JOHN; MONROY-HERNÁNDEZ, ANDRÉS; RUSK, NATALIE; EASTMOND, EVELYN; BRENNAN, KAREN; MILLNER, AMON; ROSENBAUM, ERIC; SILVER, JAY; SILVERMAN, BRIAN; KAFAI, YASMIN (Communications of the ACM, 2009)