Inspiring Science Education Academy offers the following courses, please visit and learn more about how to how to plan activities for your students, such as the Eratosthenes Experiment.
Carl Sagan - Cosmos - Eratosthenes
Using geometry to measure the circumference of the Earth.
NASA Connect Segment explaining questions about Erastothenes, the Earth's circumference, parallel lines, angle relationships, and a transversal.
Adam Savage walks through two spectacular examples of profound scientific discoveries that came from simple, creative methods anyone could have followed -- Eratosthenes' calculation of the Earth's circumference around 200 BC and Hippolyte Fizeau's measurement of the speed of light in 1849.
Here are a couple of computer-animated segments I made. They were to be part of RabidApe's Big Bang project.
The Math Forum newsletter serves as a gateway to the Net providing information about math resources and key issues in math education.
The video describes how to perform the Eratosthenes Experiment during the summer solstice (content and videos in spanish).