In educational settings, the trend of providing students with tablets for use during class is increasing. This shift is expected to encouraging encourage a transition toward active learning. However, fatigue hinders active learning. Interleaved learning has been proposed to reduce fatigue during learning sessions, but previous studies on interleaved learning did not control for the timing of task switching, possibly causing students to continue the same learning activity even when fatigued. In the current study, we hypothesized that switching tasks at the moment of fatigue can further help reduce fatigue. We developed a system that switches learning tasks based on fatigue levels (which are estimated by measuring leg movement) and examined changes in learner fatigue during its use. Evaluation experiment results indicated that the proposed method helped reduce fatigue, but the high frequency of task switching disrupted participant concentration immediately after each switch. In future work, we plan to investigate changes in learner fatigue when the system is used in group learning environments.