"You are welcome." Severus muttered nervously blushing at Lily's words. He could tell her how easy it was to do without him. He knew he was good at potions, but he also knew he attracted ridicule and bullies.
"I am sure you would have figured it without my help." Lily was a bright witch, she would have definitely figured out the mistakes, the first step she had already taken before she talked to him, she had realized something was not right.
He took the book back and put it on his potion's notes, smoothing down the worn edges.