Creating effective computer-based learning exercises requires an understanding of optimal user interface designs for improving higher order cognitive skills. Using an online volcanic crisis simulation previously shown to improve decision making skill, we find that a user interface using a graphical presentation of the volcano monitoring data reduces the effectiveness of the exercise compared to an informationally equivalent text-based data presentation format. Results are consistent with earlier work demonstrating that the over-automation of quantitative analyses in computer-based learning reduces their effectiveness in improving higher order skills. Additional research is critically needed to clarify the conditions under which user interfaces can be optimized for ease of use while not sacrificing the exercises' effectiveness in improving higher order cognitive skills.