Science competencies acquired at early years are basic and influence on children's later development. Gender differences in these early science competencies may explain the often-reported gender differences in later science abilities. Research in this field was not usually focused on pre-schoolers. In this study, we focus on the interaction between five- to six-year-old pre-schoolers and a researcher while they work on tasks about physics and astronomy in three experiments. Participants were five- to six-year-old children attending preschool in Sevilla (Spain) representing the full range of socioeconomic backgrounds. Over the course of experiments, an increase in the students' number of right answers occurred. Results supported that pre-schoolers' early science competencies are characterized by gender equality and do not explain later-reported gender differences. However, the findings showed that girls are not inclined towards scientific careers, even if they have the same scientific performance as boys.