Research on Cognitive Load Theory has shownthat measures of cognitive load can revealimportant information about the cognitiveconsequences of instructional conditions thatis not necessarily reflected by traditionalperformance-based measures. Although, theindividual measures of cognitive load can beconsidered important to determine the power ofdifferent instructional conditions, ameaningful interpretation of a certain level ofcognitive load can only be given in the contextof its associated performance level, and viceversa. This was recognized by Paas and VanMerriënboer (1993) who developed a2-dimensional computational approach to combinemeasures of test performance with measures ofthe associated mental effort in order tocompare the `mental efficiency' ofinstructional conditions. In this approach,high task performance associated with loweffort is termed high instructional efficiency,whereas low task performance with high effortis termed low instructional efficiency.Here we explore the utility of employingmulti-dimensional approaches, in particular two2-dimensional efficiency measures and a new3-dimensional approach, which combines themeasures of learning effort, test effort andtest performance. Each of these approaches withtheir associated insights and analyses may beuseful for instructional researchers, e.g. asdiagnostic instruments to identify differentaspects of efficient or inefficientinstructional conditions and can be implementedin a broad range of learning environments,including electronic environments, possiblyenabling more effective learning-task selection.