What makes Melinda a good actor?

From the text:

I am a good actor. I have a whole range of smiles. I use the shy, look-up-through-the-bangs smile for staff members, and the crinkly-eye smile with a quick shake of my head if a teacher asks me for an answer. If my parents want to know how school went, I flash my eyebrows upward and shrug my shoulders. When people point at me or whisper as I walk past, I wave to imaginary friends down the hall and hurry to meet them. If I drop out of high school, I could be a mime.