Abstract
This study characterizes conceptual relationships necessary for understanding confidence intervals through the construct of Schema as proposed in APOS theory. The research is developed through a Theoretical Analysis of the concept, complemented by an empirical exploration based on semi-structured interviews with preservice mathematics teachers who had completed a statistics course at least one year prior. This approach made it possible to identify relationships that persist after formal instruction, as well as those that fail to consolidate. The results reveal difficulties in interpreting the confidence level, in articulating the relationship between the sample mean and the population parameter, and in recognizing the role of sample size in the precision of the interval, suggesting a limited Schema. Based on the identified relationships, the genesis of a Genetic Decomposition of the Schema of the confidence interval is proposed.