"Remember Harry you have to picture it perfectly in your mind, you can't just want it to change. You have to see every detail in your mind before you cast the spell, if you haven't thought of a single detail then it won't change." Hermione said as she flipped through her own notes next to him, pointing her finger at the passage stating such in the book and then pointing at her notes on the topic. Harry nodded happily as he wrote it down in his own notes.