T1 · 5s · forgiving — letter-counting OK on the on-ramp
Read by shape — adjacent notes, or one skip apart?
What this skill is
On the staff, intervals have a shape. A 2nd is line+space adjacent (the notes touch). A 3rd skips one — line-to-line or space-to-space. Mastery is recognising the shape at a glance, not counting letters.
Common misconception
“I’ll count letters: E to F is 2nd, E to G is 3rd.” That’s correct but slow — sequential cognition, ~3-4s per 3rd. The audit tightens the latency cap from 5s (T1, letter-counting OK) to 1.5s (T5, only shape-reading is fast enough). At T3 (curriculum mastery) letter-counters fail systematically.
12 trials · structurally balanced 6 2nds + 6 3rds (shuffled per session). Pass per trial: correct kind · ≤5.0s. Pass session: ≥11/12 hits AND median hit-latency under cap AND ≥2 distinct shape variants seen.