Measuring flour incorrectly is one of the most common mistakes people make in baking and cooking. At the University of Minnesota, we conducted experiments where we learned that the biggest variable in every recipe is the cook. So standardizing measuring techniques is the most important way to ensure that a recipe works.
This is the wrong way to measure flour. Scooping flour from the container or bag directly with the measuring cup will pack the flour into the cup and you'll end up with too much flour. Even with a properly leveled top, this method is wrong.