Snape is the Slytherin Head in Hogwarts. He teaches potions. He is Harry Potter's least favourite teacher.
In Harry Potter and the Half-Blood Prince he is the new Defense Against Dark Arts teacher, and ends up killing Dumbledore at the end of the book.
Jacob's teacher snaped him about his chemistry experiment, telling him there was no way Jacob had created a perfect experiment since his father had been horrible at chemistry, but then again he was just as arrogant as his father so why should Jacob think any differently.