In the April 25, 1953 issue of Nature, James D. Watson and Francis H. C. Crick announced one of the most significant scientific discoveries ever: the double helix model for the structure of DNA. They could not have proposed their celebrated structure for DNA without access to experimental results obtained by Rosalind Franklin, particularly this crucial X-ray diffraction photograph taken by her. This worksheet use Maple to show why Franklin's photograph suggests a helix structure.