A small refrigeration plant, for teaching refrigeration theory, used a control console built to traditional design guidelines: one output in the display for each sensor in the plant. This style of console is notorious for inducing high cognitive loads on operators and for displaying redundant data. Often the high cognitive load is the result of inconsistency between the intent for displaying the data and the format of the displayed data. An interface, based on Ecological Interface Design Theory (EID) was designed and implemented. The completed interface provided the operator with information commensurate with the operator's mental model derived from the system image. During testing of the new interface the expert operator's mental model of the refrigeration system was modified due to improved observation of the refrigeration plant's operational parameters. The application achieved the desired result and reduced the operator's workload by removing a cognitive task - determining system stability -from the operator's task list.