Accurate measurement is essential to insure good cooking.
A half-pint cup is the standard. They can be had with fourths and thirds indicated.
A cupful is a cup filled LEVEL with the top. To measure a cupful, fill lightly with a spoon, taking care not to shake the cup; then level with the knife.
A spoonful is a spoon filled LEVEL with the top. First sift the material into the bowl, dip in the spoon, lift it slightly heaping, and level it by sliding the side of a knife across the top of the spoon. Do not level by pressing it.