The ABC of probabilistic literacy for good decision-making should be conveyed to children at an early stage, or more precisely, before they reach their 11th year of age. This conviction is based on the view of experts who maintain that the mathematical competencies of adults who are not especially trained in mathematical subjects are those they developed when they were 9, 10 and 11 years old. This paper will show how children can be provided with elementary, yet useful tools for decision making under uncertainty. Children, as has been demonstrated empirically, can acquire a mosaic of simple, play-based activities, by means of tinker-cubes. The results reported here were guided and inspired by empirical studies on human decision making obtained by the Centre of Adaptive Behaviour and Cognition, directed by Gerd Gigerenzer.