What this skill is

Notes appear on either the treble or bass staff. Your first job is to read the clef sign — same staff position is a different MIDI in different clefs. The bottom line is E4 (treble) or G2 (bass), 21 semitones apart. Mastery means you read both clefs without confusion within the latency cap.

Common misconception (the clef-blind trap)

“I’ll find the line/space and use the treble interpretation.” That works for treble trials but fails every bass trial — same line, wrong letter, off by 21 semitones (almost two octaves). The audit catches it via per-clef tracking: a clef-blind learner hits ~100% on treble and ~0% on bass. By T4-T5 each clef must clear independently.

How this builds on the prior lessons

Treble-staff landmarks + bass-staff landmarks taught each clef independently. Grand-staff combines them — every trial is a clef sign + a notehead, and you must read the sign first. This is the prereq for interval-reading and sight-reading, where the clef changes between hands or between systems.