In this work, an adaptation is developed of the first observation attempted by Galileo to demonstrate the heliocentric hypothesis to be correct. The objective is to enable students in their final year of elementary school to confront by themselves the same contradictory evidence that Galileo confronted during the second decade of the 17th century. The results of its implementation in two classes of 32 students aged 11-12 years are reported, and the first impressions of this pedagogical approach are analyzed.