I tap the monochord like a soap-opera aside: Middle C hums, 261.63 Hz, halved strings and 2:3 conspiracies. My thirteen-year-old, part musician, part number sleuth, charts ratios, converts decimals, tames repeating ghosts into tidy fractions. Unit 1 felt discovery; Unit 2 demanded rules — truncation, rounding, algebraic rescue — and she rose. We cheered at simplified fractions, at accurate interval tables, at the grin when a repeating decimal surrendered. Light scaffolding, fierce curiosity, neat notation. It's music, math, and character training — Pythagoras applauds, and I secretly imagine a monochord curtain call. Bravo; next: tuning, listening, experiments and hands-on practice.