The role of teenagers in society as society itself has evolved.
Tribal / semi-agricultural societies
Agricultural societies
Pre-industrial societies
Industrial societies
Mention how only in the last 100 years have people over the age of about 13 been treated more like children than like adults, and how this flies in the face of religious and cultural traditions thousands of years old (why else would ALL the coming-of-age rites hit around 13, if you were not expected to be "of age" thereafter?).