This is the scene I choose for my Project.
In the first time, Harry Potter fail to use patronus charm to protect Sirius and himself. And he thought it was his father saved them. But actually when he and Hermione go back to the past, he find out it is himself defeat the dementors.
In my opinion, I think this scene is about courage and love. And because the patronus charm looks like white flash. So I want to use some white LED lights to represent the courage. The LED will flick several times ,at last it will be permanently light up.