  Our first experience of dimension typically comes in the intuitive Euclidean
sense: a line is one dimensional, a plane is two-dimensional, and a volume is
three-dimensional. However, following the work of Mandelbrot \cite{mandelbrot},
systems with a fractional dimension, ``fractals'', now play an important role
in science. The novelty of encountering fractional dimension, and the intrinsic
beauty of many fractals, have a strong appeal to students and provide a
powerful teaching tool. I describe here a low-cost and convenient experimental
method for observing fractal dimension, by measuring the power-law scaling of
the resistance of a fractal network of resistors. The experiments are quick to
perform, and the students enjoy both the construction of the network and the
collaboration required to create the largest networks. Learning outcomes
include analysis of resistor networks beyond the elementary series and parallel
combinations, scaling laws, and an introduction to fractional dimension.
