First Zoom Level
The Bezoar is on the desk of the blonde girl sitting to the right of Hermione. It looks like a brown pebble.
Flobberworm Mucus is on a shelf above the book and to the left of the light from your viewpoint.
Horklump Juice is in the middle of the second from the top shelf at the front of the classroom.
Lethe River Water is next to Snape on the shelves.
Second Zoom Level
There is nothing to collect on this level, but it allows you to continue to explore the moment. You can turn the page of the potion book, and if you hover over the mouth of the dragon, water pours out of it. As you pass your mouse over the lantern above Snape, it swings back and forth.