To Sally in NC
To test your yeast to see if it's still active, dissolve 1 tsp sugar
in 1/2 cup warm water (110 - 115 degrees) in a glass measuring cup.
Sprinkle 1 scant tablespoon yeast slowly over the surface. Stir;
allow the mixture to sit for 10 min. Within the first 5 min, the
yeast should begin rising to the surface. At the end of 10 min, if
the yeast has doubled and reached the 1 cup mark and has a rounded
crown of foam, it is very active. Yeast that is inactive or losing
its potency will either not react at all or will not reach the 1 cup
mark within 10 minutes. In either case, discard the yeast and buy
new.