I wonder if this actually teaches you the right kind of muscle memory. I have no difficulty with hjkl for navigating in Vim, but I had trouble associating those keys with the string "move one character". Mapping from the description of the command to the key is not the kind of muscle memory I use all day.
Agreed. Perhaps a block of text/code with lines highlighted along with instructions on how/what to change them? That would give the right visual feedback and should be totally doable.
> Duplicate this line
or
> Move the cursor to the beginning of this line|