Fischer Projections of L-Erythrose
All of the images below are for L-erythrose. Rotate the images so see how the 3-dimensional model correlates with the three Fischer projections beneath it. The excercise demonstrates how all nine projections are for the same molecule. All are correct. It is a matter of perspective which one is drawn. The convention for sugars is to use the first projection on the left, with the aldehyde or ketone on top and the CH₂OH on the bottom. For typical organic molecules there is no convention for which perspective is best.
Red = Oxygen, Grey = Carbon, White = Hydrogen