The suggestions made in the second post are very strong. Here are some additional thoughts.
Scientists have apparently found that the same basic expressions are used to express the same basic emotions in different cultures around the world. For example, apparently blind persons use the same facial expressions for the same emotions as sighted people. See this link, for example:
It might be interesting, then, to compare clips taken from films from different cultures (say, American, Chinese, African, and/or Indian) to see to what degree the same facial expressions are used to expess the same emotions.
Another possibility would be to focus on films from the "silent film" era and see if you can predict how the characters are reacting, based on their facial expressions, before you read what they are supposed to be "saying."