This is the range of emotion and expression that is possible with the human face. This guy is moving - mouth, eyes, eyebrows. A great headshot technique is to throw out words and get your clients to make whatever face they want to convey that word. It doesn't have to make any sense, and a lot of times there's a genuine smile that comes right after making the silly face.
Teaching Self-Portraits: proportion vs. tracing face shapes. For grades 1-4 teach proportion. For grades 5-8 begin by having students trace a picture of themselves onto transparency using vis-a-vis marker. Students tape transparency into sketchbook for shape reference. For grades 9-12 teach both methods and introduce modeling/value
Learn to Sketch Better Portraits With Just 3 Simple Tips