ENGAGE: A Game-based Learning Environment for Middle School Computational Thinking. - Kristy Elizabeth Boyer; Philip Sheridan Buffum; Kirby Culbertson; Megan Hardy Frankosky; James C. Lester; Allison G. Martínez-Arocho; Wookhee Min; Bradford W. Mott; Fernando J. Rodríguez; Eric N. Wiebe (SIGCSE, 2015)