There we go, the missing herbs are added (potion turns mint green) and the Polyjuice Potion is ready for the very last ingredient!
Hermione has a Slytherin girl's hair that she plucked from her cloak during one of their shared lessons. Ron got Crabbe and you were left with Goyle.
As you add your hairs into the vials, the potion turns muddy brown and thickens up to the most unappealing lumpy consistency.
Better hurry up, these work best when fresh!