talk to your sister first and explain how your discovery puts both of you in an awkward situation. She needs to stop lying. Go to your parents with the information, or go together. You do not need the burden of this information as a secret. It usually gets discovered sooner or later and you will feel badly if your parents find out you knew about the deception. Go for it. Be honest.
Wayne Yankus, MD, FAAP
expert panelist: pediatrics
A mother is her child's best friend and there is nothing cute about this wall of silence siblings put up to keep their parents from knowing their misdeeds. i will just out it this way: suppose you are away and your sister. God forbids, is late, very, very late, Maybe something has happened to her, nit she's missing. Your mom will tell the cops she was being tutored. Is this when she finds out that there was no tutoring that day or on many past days? Sorry, I'd have to alert my mom to what's going on, and if that makes me a rat so be it because there are many bad people with horrible intentions out there. In addition, your mom deserves more respect than that, just as you will deserve the respect and honesty of your children. Take this from a 55 year old single make teacher.