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 the preferable example for our students and for the implementation of Inquiry method. Inquiry learning and active learner involvement can lead to important outcomes in the classroom. Students who actively make observations, collect, analyze, and synthesize information, and draw conclusions are developing useful problem-solving skills. Students will measure the length of the shadows, and find the ratio of the length of the shadows and length of the rod. They will find the angle of incidence of the Sun in its place, at autumn equinox 2018 and at spring 2019. 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!