Dance
We see a wide shot introducing us to the school dance, and under the banner we see Charlie sitting alone in the darkness on the bleachers. The imagery reveals his emotional state as he feels like an outsider, but we notice his desperation to join into life as Sam and Patrick dance.
To Charlie
Patrick gathers everyone around Charlie to raise their glasses to him in a toast. The imagery reveals how they care for him and see him by acknowledging him publicly, something he truly needs in his life. We also understand the importance of belonging in this scene.
Rite of Passage
Sam stands up in the back of the truck as they drive through the tunnel listening to "Heroes" by David Bowie. None of the three have heard the song before, and Sam celebrates by standing in this way as the song plays. This imagery shows how Sam and Patrick celebrate the unknown of life rather than falling into the darkness of judging it, and this is vital for Charlie to experience for himself.
Gift
Sam gets Charlie a typewriter as a gift before she goes away to college. The imagery reveals how she believes in him as a writer, and more than belief provides a tool for him to express himself which she knows matters for every person including Charlie.