In this paper, we describe a series of activities designed to help students construct the Type I error probability �concept of a statistical hypothesis test in introductory statistics courses. The activities are carried out in the context of testing hypotheses for one proportion. The resulting interpretation of this activity, on the part of the student, for a, after performing the activities and consequently having made the mental constructions corresponding to the notion of probability of Type I error, is �the proportion of experiments that randomly reject the null hypothesis in favor of the alternative hypothesis when in fact the null hypothesis is true�. The activities, we present, are based, from a theoretical perspective, on the APOS theory framework.

APOS theory, Type I error, hypotheses test, simulation.