The idea of the Fifth grade reading level as representing a minimum standard
for literacy has been around for a long time. I am not sure that the concept is
terribly useful, other than to underline to the curator princes that not
everyone who can be expected to visit a museum has the same vocabulary as an
art historian, vertebrate paleontologst, or whatever - something which museum
people have trouble remembering.

A better guideline is the 70 words maximum for a label, propounded by (as I
recall) Steve Bitgood and others - a limit to which I subscribe.

I also like labels set up in three levels, to wit:

a. a title (large font, bold) which gives the reader a first cut at the info;
b. a sentence or two (smaller font, bold) which conveys the gist of the subject
in a trenchant fashion, which gives a second level of info;
c. a couple other sentences (same size as (b) but not emboldened), to give a
tertiary level of info.

This gives the visitors a choice as to how deep they go in each label, which is
important, assuming you want to cater to a veriety of levels of interest. Avoid
polysyllabic words; they seldom are necessary and chiefly serve to put people
off.

There is a considerable body of research on labels, with much of it written by
Steve and colleagues. I commend it to you.

Harry Needham