We simply don’t know what Jesus did during his youth and young adulthood, besides traveling to Jerusalem yearly with his parents for the pilgrimage feasts (cf. Lk 2:41) and living with his parents in Nazareth (cf. Lk 2:51–52). Given human curiosity, it is natural to want to know more about that hidden time, but transcribing the details was unimportant to the Gospel writers.
Perhaps you could suggest an alternative project: Since one of the points of the hidden years was to live an ordinary human life, thus sanctifying the human family and human work, perhaps this teen could research what life was like for an ordinary working-class first-century Palestinian Jewish family. That would give some idea of what Jesus’ hidden years entailed.
A good place to start research would be with the book Daily Life in the Time of Jesus by Henri Daniel-Rops. The book is currently out of print but can be located through interlibrary loan.