This is a combination EQ/Art exercise. As EQ (emotional intelligence or Character Education) it allows children to explore their emotions, and the emotions of the rest of the class, and how they effect their facial expressions.
As an art exercise it helps students understand that faces have proportions and that changing one part of the face can change the meaning of other elements of facial expression.
This activity has been designed with Casual Relief, Substitute, Temporary Teachers in mind. It uses commonly available resources, is engaging, and is easy to keep in your “teacher toolkit” to be used at very short notice.