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How Big Is Earth?

posted Sep 12, 2015, 8:25 AM by Bonnie Thurber

Hello Friends and Colleagues - Middle School Teachers World Wide, 

Please register, review and begin the "How Big is Earth" project in the iCollaboratory on or after Sept 1. 

This project is funded by International Astronomical Union (IAU) Office of Astronomy for Development (OAD) in partnership with the South African National Research Foundation.

Using only the sunlight striking the Earth and a wooden dowel, students can measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. This project meets standards for Math, Science, Reading and Geography. Students receive buttons for each activity.

The second project officially begins June 1. If you start early your students will learn lots more. The dates you need to remember are Sept 1, and Sept 19, 20, 21, and 22. All angle measurements are due by Sept. 23. Raw measurements should be taken on Sept. 19, 20, 21 or 22. If those days are cloudy or your students are on vacation, please use Activity 7a or 7b to collect the correct measurements and post them early. 

  1. How Big is Earth is for classroom students ages 10-15 years.
  2. The project-class is held in the iCollaboratory (a Moodle and Google Apps for Education private domain)
  3. In Moodle, the project is found at
  4. All participants need a username and password to log in.
  5. If you are a teacher and need  an iCollaboratory user name, go to the address above and click create account.
  6. To create accounts for your students please view and send a note to
For more information, please contact

Thank you,
Bonnie Thurber and the iCollaboratory Team