Resumen: The intuitions and heuristics on the probability are evaluated in 257 engineering students through a questionnaire of eight closed items, and they analyze the arguments of 148 of them in an open item. The results indicate a high variation in the qualitative assignment of the probabilistic intuition in situations of uncertainty and the existence of correct and incorrect intuitions of the students. We propose a teaching of probability that relates theoretical and practical understanding of meanings of probability, from the intuitive to the axiomatic, through the qualitative estimation of probabilistic intuitions as a degree of personal belief, and the explicit confrontation of diverse heuristics with formal knowledge of probability.