The level of learners' expertise has been used as a metric and diagnostic mechanism of instruction. This metric influences mental effort directly according to the applications of cognitive load theory. Cognitive efficiency, an optimal measurement technique of expertise, was developed by Kalyuga and Sweller to replace instructional efficiency in e-learning environment for dynamically adapting instruction. But mental effort, a factor of cognitive efficiency, is assessed by a node mode measurement technique which discontinues instruction and causes interference. This research proposes a new adaptive e-learning measurement technique which assesses learning effort in a dynamic, real-time, and non-interference instructional process. The learning effort curve is a key diagnostic to enhance interaction between instructors and learners in an adaptive e-learning instructional process. (Contains 3 tables and 3 figures.)