Eratosthenes Experiment_Ireland 2015

Eratosthenes Experiment_Ireland 2015
This is a schools community of Dublin City University
Domain: Science

This is a Community to support schools participating in the Eratosthenes experiment at Noon local Irish time on Tuesday 22nd September 2015.  Weather not permitting (shadows not available!) in the Resource section below an outline of how to complete the experiment is also available.

The Lesson Plan is well structured with lots of background information and will guide you through the steps of the experiment.


1. Find the time of your local noon at your location. Please use the web-based Solar Calculator or the Stellarium software (a short guide for using the Stellarium software to calculate your local noon at your location can be found here).

2. Take a one-meter stick (H= 1 meter, see Image below) and place it vertically to the ground. Ask your students to measure the length of the stick to make sure it is one meter long.

3. At the time scheduled to conduct the experiment, ask your students to measure the length of the stick’s shadow (length S in the figure below). Repeat the measurement 5 times and write their values down in your notebook if you do not have access to the internet. If you do have access to the internet, enter in the values in the form found in the 'Submit Your Data' area in the Lesson Plan on the website (this area will be activated on the day of the Eratosthenes Experiment).  

4. Provide the students the value for length (L) of the third side of the triangle in the picture below or ask them to calculate it themselves by using the Pythagoras Theory (L2=S2+H2). Write the value in your notebook/online.

5. Calculate the distance using Google Maps between your school and the school you have matched up with. (A short guide on how to perform the measurement can be found here). Provide the students with the value of this distance between the two schools. Write the value in your notebook/online.

An Irish language version of the Lesson Plan will also be available and the link will be provided to you on request by

Please send any queries to

The best of luck everybody - enjoy the day!                                        


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Created on: 03.03.2015
Last visited: 23.06.2020