Silas nodded to himself as he watched the blackboard. Most of his classmates were calling out answers he wiukd have given. Sighs.

After a moments thought and a serious FROWN at that Kettlebum girl from his own house, he raised his hand. "Sir, the measurement of ingredients needs to be precise or it could change the properties of a potion. I mean... adding three of this and two bunches of that could make a completely different potion."