Working memory and planning are fundamental cognitive skills supporting fluid reasoning. We show that 2 games that train working memory and planning skills in school-aged children promote transfer to 2 different tasks: an attentional test and a fluid reasoning test. We also show long-term improvement of planning and memory capacities in 8-year-old children after playing adaptive computer games specifically tailored to entrain these cognitive functions. Working memory capacity expanded from 5 to 7 items by using our games. Furthermore, steady progression in the task indicates that this capacity can be trained rapidly. Planning abilities persisted in a nonmarkovian form of play, where a move is highly influenced by previous moves, avoiding back-ups. Here, we introduce a public and growing platform (http://www.matemarote.com.ar/) developed for this research which has the potential for wide use in educational research.