In this scene we learn that students graduate from school at the age 12. Lina is assigned Pipeworks labourer and Doon is assigned Messenger. Doon and Lina agree to trade jobs even though they are not aloud. If Boon and Lina didn't trade jobs then Boon couldn't work to fix the generator and save the Ember. Lina wouldn't have found out the box.
Blue sky and goodbye.
In the scene Lina finds granny pulling everything out of the closet.Poppy is on the floor playing with an open and empty box. There are tiny paper in the floor that had printed letters on it. those papers are the instruction to get out of Ember. The instructions might be connected to the generator.
In this scene when Lina wakes up she finds Granny has a fever. Lina goes to the town to find the town doctor. The doctor comes to check on Granny. Lina colours on a soup wrapper and colours the sky blue. Granny tells Lina to go to sleep. Lina wakes up to find Granny and Granny has passed in her sleep. Granny knows lot's about Ember. Mrs.Murdo has to take care Poppy and Lina.
Lina,Poppy and Doon they will finally see the sun and have blue sky. Also when they escape they will find some animals. Also they will give a note to the city that says there is a way out of Ember.