Okay—picture a string, taut and small; I pluck it and the world tilts: high, bright, like a bell. We will map sound to numbers, neat Cornell notes, tidy margins, little heart doodles. Pythagoras sits beside me (ancient, curious), a monochord between us; he halves the length and the pitch becomes one octave higher—2:1, clear as morning. We label the sketch: bridge, nut, vibrating length, node. We measure, we ratio, we write: 1:1, 2:1, 3:2, each interval a friendship of numbers. Assessments: diagrams, neat labels, concise summaries, precise ratio notation, explanations that use scientific and musical terms. Proficiency means accurate labels, clear causal links (shorter length → higher frequency), and historical connection to Pythagoras. This pre-unit is a soft, bright doorway to composition, analysis, performance—math and music holding hands, walking toward harmony. Students prepare neat Cornell notes, a short summary, and an illustrated monochord sketch for assessment and reflection and creativity.