Thirds
The first genuinely useful stopped double stop. Thirds show up constantly — in real repertoire, in harmony exercises, and as the double-stop version of the triads you already know from Stage 4.
The shape: higher finger on the lower string
To fit a third between two adjacent strings (which are tuned a 5th apart), the lower string takes the higher-numbered finger, and the string above takes a lower-numbered finger — a "skip one finger" shape.
How to play it
Place both fingers together, not one after the other. Bow across both strings evenly and listen for the third's bright, slightly buzzy ring when it's in tune.
Major or minor is a low/high choice
Exactly like a single note, which low/high variant you choose changes major to minor — the finger numbers don't have to change.
The tuning check: wiggle until it locks
Double stops are tuned "by feel and by wiggle," not by finding each note in isolation first.
Play the pair, then gently adjust the finger spacing until the buzzing/beating settles into a
clean, still interval — the same beating-tone check Stage 0's tuning and Stage 4's
tuning-by-ear already taught you for open strings, now aimed at two stopped notes with
nothing open to lean on.
Try it
Try
Play the major third, then the minor third, several times each, wiggling the fingers slightly until each one locks into a clean ring. Then alternate between them — major, minor, major, minor — and notice how small the finger adjustment actually is for such a different sound.
The usual mistake
Placing both fingers as if tuning each one separately against an imaginary open string, then wondering why the pair still sounds sour. There's no open string to lean on here — the two fingers have to be tuned to each other, which takes active listening every time, not a fixed hand shape you trust blindly.