It has already been proven that peer tutoring is an effective way to engage students in learning. However, without technology support, it can be difficult to conduct peer tutoring program in a classroom. We propose a system called P³T that supports peer tutoring in one-to-one digital learning environment. P³T facilitates peer tutoring by scaffolding both tutors and tutees to prepare for the tutorial session and facilitating their elaborations during the face-to-face tutoring. An experiment was executed to test if the P³T system can help the activity go more smoothly than those without P³T system. This paper discusses the design of P³T models and system, and reports what is found in our experiment.