Actually we tend to use reciepies in cup or spoon measures... being of 'an age' knowing my imperial measures for lots of items - 1 heaped tablespoon = 1 ounce so makes it easy really.
would love a set of balance scales though - we live in hope of finding some at a reasonable price
We have balance scales on the playdough table & pointer ones for recipes, but i usually count spoonfulls, how many spoons of flour to get to 4 oz & how many sugar? - leads to LOTS of discussion point.
I love cooking with the children - its my fave.