Right... so Lily wasn't exactly trusting her magic at this point, even though the Gryffindor prefect had explained how magic worked. So after the professor called them back to order and alike, the third year just really didn't want to have to try again with the spell right now. Perhaps later, after Louisa had helped her with her wrist a bit. So she put her left hand in the air. "Um... Professor.... Can we maybe take our trashbags with us so that we can practice the spell later? Because I didn't really manage to get a shirt of any kind..." Because she turned it into a fabric and accidentally lit it on fire... so... she didn't exactly want to do that again right now.