Question from a Catechism Student

Question from a Catechism Student (7th Grade Boy) Q. What if someone sins after God brings us all to heaven? The question asks about what will happen if a saint (or maybe an angel) sins after being made perfect and brought to heaven. Before we answer this question we must ask another question, which may be what the student really meant to ask. Is it possible for a saint or angel who has entered the state of perfection in heaven to sin?  This is a good question considering that Satan was a...