She never expected magic.
She knows mostly how it works; her mother's cousin and her husband are awful but they still send her off to school and occasionally she can get away with sneaking off to the library. So when her environment is replaced with stars, she has a pretty good idea of what happened.
She doesn't do anything with it immediately. Her mother's cousin is right there yelling at her, that wouldn't end well. So she takes it stoically until the woman dismisses her to go do chores, and she sneaks upstairs, skipping the squeaky step, and waits until the sound of footsteps suggest that the grown-ups are in the back half of the house and opens the big window in the front hall and goes back to the starscape and puts on a pair of swan's wings and flies away.