The European Association for Astronomy Education (EAAE), in collaboration with the Bibliotheca Alexandrina of Egypt and the participation of schools from all around the world, performed the Eratosthenes experiment on 21 June 2010. This activity has been selected as one of the finalists in the 11th international prize organized by Ciencia en Accion. The well known Eratosthenes experiment consists of calculating the circumference of the Earth without leaving one's own place. The goal of this activity was to create an international network that reproduced the Eratosthenes experiment all over the world and supplied the scientific knowledge needed to perform the measurements. Each participant school made the calculations to infer the Earth's circumference and shared the results through a webpage created to this end and two live international videoconferences. Schools from 20 countries belonging to the five different continents participated in this activity and the intergroup communication that was achieved motivated the students, who could better understand the scientific method beyond the experiment. The webpage created by the EAAE gave support to this activity and functioned as a meeting point for all of the participants. The students from participant schools used it to share information about the methods that were employed, the problems that they had while performing the measurements and the results of their calculations. The EAAE webpage supplied complementary material about the dynamics of the Earth-Sun system, which the teachers used as a background to prepare the experiment. (Contains 4 figures.)