While I don't find the soil triangle abstract, I was worried about my
consistency in descriptions, so I ordered a couple of cheater's helpers.
 
F. W. McCollough Co, 3101 Elkridge Ct., Beltsville, MD 20705, USA
 
This company makes both a geotechnical gauge and a sand gauge that are
very useful.  They have charts for rating angularity, grain frequency,
some colors, descriptions, and MOST IMPORTANT they have v. coarse, coarse,
medium, fine, very fine sands, and silts glued to the cards.  They are
inexpensive and I ordered mine through Forestry Suppliers.
 
Forestry Suppliers also carries a similar credit-card sized package with
the same material put out by Sigma Gamma Epsilon at Kent State University.
 
Obviously, you will still need to show the students or field techs how to
judge the amount of clay in your clayey silt or your very fine sandy
clay....
 
hope this helps...
 
Tim Scarlett