The "cube" factor that Bruce mentioned refers to what happens to the volume of air that the wing displaces, I believe. This is important, because it dictates the weight that the wing can effectively lift.
By way of example:
A 1/5 scale plane (2.4" = 1') has 20% more span and chord than the same model at 1/6 scale (2" = 1'). The area factor of enlarging the model by 20% yields a 44% increase in wing area, as already described. The real bonus (as I see it) is that the VOLUME of the wing has increased by about 70%, because the thickness of the wing also increased by 20%.
That's why larger models fly well with higher wing loadings. A 1/6 scale model that flies okay with 22 oz/sqft wing loading would work really well at 1/5 scale with 30 oz/sqft loading.
[The foregoing explanation courtesy of Dave Platt, from his "Scratch This" series.]
pj