The correct order is:
f (There is a knothole in a tree, where Boo Radley leaves things like pennies and gum, thereby creating a bond with Jem and Scout)
b (When Scout watches the house burn down, she doesn't notice that Boo steps out of his house and puts a blanket around her shoulders)
e (Dill dares Jem to touch the back porch of Boo's house, and Boo's father tries to shoot them)
c (In the process of running away, Jem loses his pants. When he returns to retrieve them, he finds them mended and folded)
d (One day, the children find that the knothole has been cemented, perhaps by Boo's father)
a (the snowfall correlates with the day that Tom Robinson is arrested - Nov. 21st).