This holistic multiple-case study sought to examine how students' learning changes when transitioning from face-to-face to online instrumental lessons in a one-to-one setting. Specifically, as this was a pilot research, it explored the students' sight-reading, aural skills, lesson engagement, and motivation to practice. The participants interviewed in this study were ten young, London-based students at beginner and intermediate levels, who had been taking online piano lessons -- led by the same teacher as for their previous in-person classes -- for four months. Furthermore, five instrumental teachers from the UK were interviewed so as to gain their reflective insight into teaching and learning processes, and to discover their online teaching experiences. The findings revealed that, while most students became more independent, both the students and their parents reported that the teacher's physical absence had influenced the learning. The absence of such factors as non-verbal communication, gestures, scaffolding, and a tactile approach had affected not only the learning but also the students' levels of engagement and motivation. While most of the teachers were satisfied with teaching online, the students and their parents preferred face-to-face lessons, reasoning that the lessons were more productive and beneficial when conducted in-person.