The two most commonly used parameters of crater shape are the diameter of the rim crest (D) and the floor to rim depth (d). However, the widespread application of d/D has limitations. This paper provides high ability students with the opportunity to use real scientific data to derive the depth/diameter ratio of rimmed (d:D) and rimless craters (ds:Ds). Data from the rimless craters can then be used to estimate the volume of ejecta material excavated during an impact cratering event.