The first great STEM challenge of IES Carlos III is here!

If you got  here because you have received a message from one of our  researchers… Thank you! And welcome.

You have shown interest in this curious initiative and this is very important for us (for them) since one of their achievements in this first great challenge of the advanced course consists of acting like a small company that has to achieve a series of objectives.

Eratosthenes experimet

The first goal consists on convincing students and/or teachers from the United Kingdom (specifically, from centers that may be found near Bristol, Manchester and Liverpool) to collaborate with them in repeating the Eratosthenes experiment that led him to calculate the Earth’s radius with astonishing precision. The choice of geographical areas is not arbitrary, since it is about carrying out the measurement in areas that share longitude (the same geographic meridian) from different latitudes. Our High School is located in Roquetas de Mar (Almería) and its longitude is -2.56936 with a latitude of 36.82287.

The choice of the indicated cities is conditioned by their location:

Bristol: 51.45451, -2.58791

Manchester: 53.48075, -2.24263

Liverpool: 53.40837, -2.99157

map with longitude


If the longitude is not shared exactly, do not worry, it is not a problem at all. In fact, Eratosthenes himself made a mistake in thinking that Alexandria and Siena (Aswan) were on the same meridian (but not).

The coordinate error will not be a problema but a great opportunity to make corrections of the data using mathematical tools.

What do we need from you?

Once you have decided to participate we will agree on a day, when your city and ours are sunny, and we will measure the shadowcast by a pole placed perpendicular to the ground at noon with the highest posible precision (a series of measurements will have to be made following a few rules, and keep a record with the results). Several photographs should be taken and the process must be recorded on video. That’s it, unless you want to get a little more involved.

What do we offer you?

A closer collaboration in the project.

If you are a teacher and you are interested in sharing the knowledge that our 4th ESO students (15 to 16 years old) are receiving about astronomy, solar physics, geodesy and mathematics, we can create a virtual classroom for all our students to interact and learn reciprocally. Our students speak English and study it as a foreign language so it could be the working language and they have the support of two other teachers who also speak the language, the engineer Francisco Javier Luque and an English teacher , Marta Sánchez, who is also an eTwinning ambassador in our region.

If, as I hope, you are interested in joining or have any additional questions, you can contact us at:

A / At. Prof. F. Javier Luque (Project Coordinator)

Again, thank you very much for your interest in our initiative and we look forward to collaborating with you on this project in which we surely will all learn a lot.

Javier Luque.



Header image:  / CC BY-SA 3.0


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