From Zero to Mozart
Stage 1First position & the staffLesson 27 of 43 · Reading

Reading in D and A

G major was one sharp. D major is two (F♯ C♯); A major is three (F♯ C♯ G♯). The reading rule doesn't change — the hand shape does.

D major — two sharps

58 bpm
D major up the D string. F is F♯ (high 2); everything else natural. This is the Long, Long Ago key.

A major — three sharps

58 bpm
A major up the A string. C is C♯ (high 2). This is the Twinkle key — Suzuki Book 1 lives here.

The same shape, two keys

58 bpm
The shape do–sol–la–ti. In G major it is G, D, E, F♯.
58 bpm
The same shape in D major: D, A, B, C♯. Same solfège, every letter changed, a different hand.

The usual mistake

Forgetting C♯ or G♯ from the signature — playing a natural where three sharps were declared at the front. In A major especially, the 2nd finger (C♯) sits forward on the A string every time.

Try

Play the do–sol–la–ti shape in G, then in D. Sing "do sol la ti" both times — the syllables stay put; the letters and the hand both move.