In art and design I try and get the student to focus on how best to create a composition that works visually and to aid in that development of their visual vocabulary the concept of the Golden Ratio or Golden Mean comes up, this illustration is created to assist in visualizing the concept.
This assists the artist in seeing how this mathematical process affects how we view things and the overall concept of good composition. Also called the Fibonacci Spiral or Divine Proportion, it helps lead the viewers eye through the composition and allows for a more natural flow through the artists work. Creating a more balanced and pleasing experience for the viewer.
I originally used Illustrator as I am fortunate enough to have a educators subscription to Adobe. I could only save the image as a PDF or EPS from there so I took it into Photoshop and created it as a JPG so it visible as more than just a link.
To add additional text to it to allow the viewer to see how the ratio breaks down I just added those in Photoshop.