A scale degree is a note’s role inside a key: 1 is home (the tonic), 5 pulls toward home, 7 leans on it. Hearing degrees is hearing musical function.
The same physical note plays different roles in different keys, and your ear cares about the role, not the letter. Functional ear training (the Benbassat method the app follows) plays a cadence to establish home, then asks where a note sits relative to it.
Once degrees are automatic, melodies stop being sequences of mystery pitches and become sentences: home, away, tension, resolution. Transcription and improvisation both collapse into this one skill.
Common questions
What are scale degrees?
Numbers 1 to 7 naming each note’s position and role in a key: 1 is the tonic (home), 5 the dominant, 7 the leading tone that pulls back to 1.
What is functional ear training?
Training that teaches you to hear each note’s role relative to the key center, rather than naming absolute pitches. It transfers instantly to every key.