  The current status of calculations of simple nucleon structure observables is
reviewed, with a focus on the axial charge. A major challenge is the
combination of an exponentially decaying signal-to-noise ratio and the need for
large source-sink separations to eliminate excited-state contributions; efforts
to understand and deal with this problem are the focus of the largest section
of this review. Finite-volume effects and chiral extrapolation are also briefly
discussed.
