In early childhood education and therapeutic settings, musical performances are often improvised to meet children's developmental needs. While such improvisation plays a vital role in supporting communication, emotion, and engagement, it has rarely been systematically described or analyzed. This study introduces a method for documenting and interpreting improvised piano performances used by educators and therapists, with the goal of making context-sensitive musical expertise more visible and transferable. We propose a dual-layer labeling system that captures both the type of musical activity (e.g., singing, movement, instrument, listening) and the performer's real-time intention (e.g., learning, enjoyment, interaction). This structure is combined with two simple acoustic indicators—horizontal and vertical note density—to quantify the texture of performance. Data from 41 musical segments were collected across daycare, kindergarten, and therapy settings. Results show that even when the same song is used, performance characteristics vary measurably depending on children's states and pedagogical aims. Comparative analysis with Orff and ISO frameworks suggests that the proposed approach adds finer granularity to practice-based analysis.