Second position
2nd position has no landmark of its own — no thumb touch, no hand-frame copy. You find it by ear, or by shifting partway back down from 3rd. That's exactly why this course teaches it after 3rd and 5th, not before: it's easiest to learn once you already have two solid positions to triangulate from.
The note map
What it's actually for
2nd position rarely earns its own long passage the way 3rd or 5th do. Its real job is smoothing — reaching a note just outside 1st position's comfortable top without the bigger jump to 3rd, or avoiding a string crossing that would otherwise interrupt a slur. You'll meet it most often as one note in an otherwise 1st- or 3rd-position phrase, not as a place you settle into for long.
Try it
Try
Shift up from 1st position on the D string toward 3rd, but stop halfway — check your 1st finger against F (2nd position) using the example above or a drone. Then do the same on the A string, stopping at C. Un-shifting partway down from 3rd is often the more reliable way to find 2nd, since you already have a known position to measure the distance from.
The usual mistake
Practising 2nd position as if it needed its own repertoire, the way 3rd and 5th do. It doesn't — its value is entirely in smoothing single moments inside music that's otherwise anchored in 1st, 3rd or 5th. Spend your practice time on the transition into and out of it, not on dwelling there.