I think that fat eighths should be 9" x 20" -- a quarter yard cut in half.
It gives a lot of ways to use the fabric and so on.
Fat eighths cut that way would be great to use for I Spy quilts.
I've done 3 I Spy quilts with larger hexagons and triangles. Most of it I could get from fabric remnants I had from other projects. Some I bought fabric for. Some I bought fabric for other projects and enough to cut hexagons from too. Loved fabrics where I could get several different hexes from the same fabric. <G>
Pati, in Phx