For many band teachers who learn to teach beginning flute, the so-called “kiss and roll” method of teaching students to form an embouchure is what they are told is the quickest and most effective way to learn to direct the air into the blow hole at correct angle. From my perspective as a flutist who has taught many beginning flute players, this method is based on a fantasy. The fantasy is that we all have the same size and shape lips. If we center the blow hole between then lips and roll it down, it will be in the best position for making a focused sound on the flute.
In reality, the “kiss and roll” method causes more problems than it solves. For the majority of flutists, the end result is that the flute winds up too high on the bottom lip. This results in a small sound which is often sharp. It is also impossible to develop fullness and power in the tone because the transit time (the time from which the air exits the aperture to when it hits the blowing edge of the embouchure hole of the head joint) is too short. Another persistent problem is that students continue rolling the flute down into position long after the need for such a crutch has passed. It becomes an annoying and unnecessary mannerism at best, and a real impediment to developing a mature, characteristic tone at worst in more experienced students.
So what to teach instead? Bring the headjoint into playing position from below by bring the curve of the lip plate to rest against the chin. Then bring the edge of the blow hole up to about the bottom edge of the lip. The crisp edge of the lip plate is very easy to feel at the transition between the lip and skin of the chin. Then teach the students to aim the air at the opposite edge of the lip plate to make a sound. Depending on how full the bottom lip is, the best position can be higher or lower on the lip.