A good lesson on the 12 disciples could focus on the various occupations that the disciples left when they chose to follow Jesus, or it could focus on their interactions with Jesus. Both lessons would provide a deeper look into the four canonical Gospels.
Focusing on the occupations of the disciples can help to highlight and add a layer of clarity to the exemplary life of Jesus. Peter, Andrew, John, James and Phillip were simple fisherman, while Matthew was a tax collector and Simon was a zealot. Fishermen, in Jesus' day, would not have been as educated, tax collectors would not have been thought well of, and zealots were fiercely patriotic Jews that would often murder in acts of secret rebellion. Focusing a lesson on the behavior of such men around Jesus and Jesus' behavior around them can serve as a tool by which to find a relation between students' characteristics and those of the disciples.