This is the second level in Year 7 Part 2 and takes place in Hogsmeade and in Hogwarts castle. Nothing too difficult to deal with here except for a relatively confusing "Student in Peril" situation.
In the first area of the level you will have to acquire 3 ingredients to complete a potion. One of these ingredients, a popsicle, is frozen in a block of ice which requires Ron's Deluminator to melt. It is held by what looks like a Student in Peril but is actually NOT. When you free him he drops the popsicle, gives you some studs, and disappears.
The real Student in Peril is in the very next area (the Room of Requirement in Hogwarts). He is hanging from the rafters on the lower left corner above two girls that are clapping.