When preparing ingredients for baking, it can be bothersome and messy to have to sift ingredients before using. Whisking them will incorporate air in the dry ingredients in the same manner as sifting.
When measuring dry ingredients, add enough dry ingredients so that it is heaping over the top of the measuring cup by lightly spooning the ingredients into the cup. It may be beneficial to stir dry ingredients, such as flour, powdered sugar, baking soda and baking powder to aerate the ingredient and remove any lumps that have developed. Do not shake, tap, or pack the ingredient into the cup. If measuring with spoons, pour or scoop the ingredients into the spoon.