I've been contacted offlist and asked to qualify my statement about the Fibonacci series. Firstly, I should state that I'm no mathematician so really don't want to get into arguments about math(s).
However, the attached file contains a spiral drawn using the Polyline tool with Tangent Arc mode selected. Each segment of the curve uses the next in the Fibonacci series as its radius and a sweep of 90 degrees. Numbers are 1, 1, 2, 3, 5, 8, 13, 21...
The result is also I believe known as the Golden Spiral. It is not logarithmic, but is easy to use in a Landscape design scenario because it's easy and clear to set out on the ground.
Sophie - I will also Skype this file to the rest of your student colleagues!