Geoscience education relies on figures and diagrams to convey visual and spatial information to students, but the effectiveness of those images can be difficult to assess. Additionally, an individuals' understanding of new spatial concepts is developed from a framework of their existing knowledge and can help or hinder development of newer concepts. Diagrams need to accurately convey information without over-simplification and without providing extraneous detail that muddies the intended message. For example, a common misconception held about groundwater is that it exists as underground pools or streams like how water is found on the Earth's surface. Many groundwater diagrams use a blue shaded area to represent the location of groundwater underground; however, this practice may reinforce the misconception that groundwater is underground pools or streams rather than filling pore space of rock and sediment.

In this study, we assessed undergraduate students' knowledge of surface and groundwater features using diagrams to determine how different features of the diagrams might affect their answers. We designed the diagrams with varying levels of dimensionality and/or complexity with respect to color and texture, altering the amount of detail provided by the diagrams. Participants were recruited from undergraduate introductory Earth Science courses at two American universities and received extra credit for their participation. The majority of students surveyed were non-science majors taking their first Earth Science course. Seventeen multiple choice and click-on-diagram questions were administered at the beginning of the semester prior to instruction. Students were randomly assigned into one of three groups based on the sequence of the questions they received, to test for ordering affects in the variably complex diagram questions. The results of this study provide researchers, instructors, and instructional designers with evidence for the level of complexity that will maximize student understanding with ground and surface water diagrams.