The Easy Java Simulations Modeling and Authoring Tool is needed to explore the computational model used in the Eratosthenes Model.

The EJS Gnomon model simulates the shadow cast by a gnomon (the part of a sundial that casts the shadow) over the course of a day for any day of the year and any latitude on Earth.

changes

tilted by 23.5 degree to simulate topic of cancer
color code the checkbox
add distance = arc length drawing
add text as hints
add top Gnomon checkbox
add shadow checkbox
22June 2012
add Google earth picture
add assessment for learning input fields with feedback for Radius of Earth and Circumference of Earth

credits to Todd Timberlake!
i didn't make this, just remixing to customize it to suit the Wikipedia entry http://en.wikipedia.org/wiki/Eratosthenes
enjoy!