ALEXANDRIA: The Bibliotheca Alexandrina celebrated Eratosthenes (276-195 c), one of the prominent head librarians of the ancient library, with a day of science fun where about 500 Alexandrian preparatory school students re-performed the experiment he is now most remembered for. On the noon of the summer solstice, the sun appears at the zenith of the sky at the Tropic of Cancer; this means that objects observed there and then would simply be without shadow. Although slightly above the Tropic of Cancer, modern day Aswan is where this phenomena has been long noticed. By measuring the shadows of objects at the same time in Alexandria and knowing the distance between the two cities, Eratosthenes easily arrived at the circumference of the Earth. As brilliantly simple this method is, his result of 39,690 km was quite accurate having only 1 percent error. Since its conception in 2003, the Eratosthenes festivity has been regularly celebrated on June 21 of every year. The event attracted more schools outside of Alexandria: three schools in Aswan, one in Virginia in the United States, and 300 in Argentina. The Bibliotheca prepares the participating schools by conducting a training session for the teachers on related materials which they cover in class 20 days in advance. It is designed for preparatory school students and includes a series of activities that revolve around Eratosthenes s methodology. This year, a history lecture about Eratosthenes the man and another about other methods of measuring the Earth's circumference were presented to the students. After about an hour of working hard and having fun in the blazing sun to get precise measurements of the shadow of a pencil, the students in Alexandria had the chance to compare their results with the other schools in Aswan, Virginia, and Buenos Aires. Video conference connection problems aside, the students were thrilled to see others their age performing the same experiment. Each of the international group presented their results and a brief summary of how they did their experiments. After the final results of the schools have been compared, one school teacher in Alexandria commented that the students should also be taught about simple statistical properties of their data, like standard deviation. Although, a simple plot of the data points would have helped the students get a better idea of which groups had more consistent, better quality data, and of how their data was spread out, it's hard to say that the absence of statistics affected the core purpose of the event, which is teaching students that science is an exciting cooperative activity. The event and the lectures included, however, didn't offer an answer to the question of why this experiment is important, or even why Eratosthenes did it. What do we gain by learning the Earth's circumference? It's likely many of the participating students didn't develop an answer to this question, let alone an appreciation of the question, by means of the event. Yet, this didn't take away from the success of the event. Eratosthenes day wasn't just another school assignment. It could have been much more successful if it made the students think more about the reason behind the experiment as much as it made them think about its details, if it made them examine the importance of the experiment after they learn it.
