Ms.Garcia is an i-ready Character used in the old I-Ready lessons. The only recorded lesson of her is here https://www.youtube.com/watch?v=EnsqdHm2_lc&t=33s
EDIT: Sorry, the link has been taken down, you can do the lesson yourself here with the Tutorial and Quiz:
There isn't really specific lessons she was used in but the link at the top will show you a recorded lesson. She was used in Reading lessons and Math lessons.
She was known as a really creepy I-Ready character but she was at least good enough to teach off a few lessons