The 3-black-group landmark

The 3-black cluster anchors four white keys, not just F. Reading outward from the cluster:

• F · the white key just left of the 3-black group.
• G · the lower white key inside the 3-black group (between the first two blacks).
• A · the upper white key inside the 3-black group (between the last two blacks).
• B · the white key just right of the 3-black group.

Reading G and A from position inside the cluster is faster than counting up the alphabet from F under time pressure.

How the tiers force the skill

At Tier 1-2any octave’s landmark counts. At Tier 3+ each prompt names a target octave (lower / middle / upper) and your tap has to be in that region — forces real cross-octave use of every 3-black group on the keyboard.

Builds on keyboard-landmarks; with two-black-key-groups it feeds middle-c-orientation and every later reading lesson.