Stubborn Old Man
We see Christopher standing at the top of a hill as Ron sits in his truck at the bottom. The camera shoots from Ron's point of view and the imagery reveals that life can still be lived and learned by watching those younger than we are. And Ron shows this as he climbs to Christopher.
Tolstoy
We see Christopher reading Tolstoy's Family Happiness and the sequence ends with him smiling outside of the school bus. But his smile turns to a confusing look, troubled within. The imagery reveals that while Christopher is learning about who he is, what he believes and how he wants to live he senses something is off within him. While he is connected to the wild there appears to be something missing.
Writing
We see close up shots of Christopher writing throughout the film. This imagery reveals how he kept a journal of his intimate thoughts, it brings the reality of this true story into focus so that we as the audience don't lose track of the fact that this was someone's life, not a fictional account meant solely for catharsis but a recounting of a young man's journey.
Communing
Christopher has found his magic school bus in the wild and we watch as he witnesses the wild herds of animals pass by this land untouched by mankind. The imagery creates a connection between him and the land and ultimately reveals a communion that is natural and awe-inspiring from nature to man as Christopher wells up with tears at the wonder of the creatures he see living free before him.