Students from all continents cooperate and collaborate to reproduce one of the science's 10 most beautiful experiments of all time: Eratosthenes' measurement of the Earth's circumference. Although Eratosthenes experiment known for more than 22 centuries, it is always preferable example for our students and for the implementation of Inquiry method. They will find the angle of incidence of the Sun in its place, at autumn equinox 2016. The data will be compared with the data of the partner schools. They know that the Earth is round, but will simply calculate the approximate circumference of the Earth!