Bravo — snap, hum, la‑la! Our thirteen‑year‑old has computed a Pythagorean C scale from Middle C (261.63 Hz) to C' (523.26 Hz) using monochord ratios (1:2 octaves, 3:2 fifths, halving and two‑thirds for derived steps), systematically doubling and halving octaves. Her calculations demonstrate clear multiplicative reasoning, inverse proportionality, neat notation and consistent units — truly exemplary. This work neatly ties ACARA v9 The Arts (Music) with Mathematics (Number & Measurement). Recommended next steps: compare Pythagorean and equal temperament (calculate and listen), verify with a hand‑made monochord or tuning software, practise focused ear‑training, keep a short reflective journal, and present a one‑minute demo for the portfolio. Encore! Cue tiny celebratory grocery‑bag dance — la‑la, snap — and a brief vocal flourish. Proud parent: please badge that musical numeracy soon. Would love a short assessment rubric, teacher comments for the homeschool report, and a suggested badge criteria to celebrate mastery — thank you, sincerely.