The raw material: seven letter names (A–G) repeating every octave, the staff and its clefs that pin each one to a line or space, the black keys named by accidentals (a ♯ up a half step, a ♭ down), and the fact that one sound can wear two names — C♯ and D♭ are enharmonic. Click the keyboard to see and hear each note spelled both ways, then drill reading a key signature.
Every major key has a unique fingerprint of sharps or flats. Name the major key from its signature (its relative minor shares it).