1. Inside the room of requirement.
2. In the sorting hat.
3. In the Chamber of Secrets.
4. In the fireplace inside Hagrid's cabin.
5. With Aragog's colony.
6. In the sleeves of Ron's R sweater.
7. Mixed in with the leaves in a Divination tea cup.
8. In the vanishing cabinet in the room of requirement.
9. In Luna's lost sneakers.
10. In the staircase to the Gryffindor girls' dorm.
11. At the top of the Owlery rafters.
12. Taped behind Moaning Myrtle's toilet.
13. In the entrance to one of the passageways from Hogwarts to Hogsmeade.
14. In a different passageway from Hogwarts to Hogsmeade, moved while people are looking.
15. On a moving staircase as it's moving.
16. As a constellation in the great hall ceiling.
17. Under the seat cushions on teacher's platform in the Great Hall.
18. Under a mandrake pot.
19. Anywhere in the Ravenclaw tower.
20. Under the cushion to one of the armchairs in the Hufflepuff common room.
21. In the potions closet.
22. Under the trapdoor when Fluffy isn't looking.
23. Behind one of Umbridge's framed proclamations.
24. Mixed in with the trophies in the trophy closet, since the Afikomen is the ultimate trophy.
25. Between the towels in the Prefects' bathroom. Safety against crumbling!
26. Tied to Mrs. Norris' collar (if she lets you get that close).
27. In front of the lens of a telescope in the Astronomy tower, so you can only see it when you look through the eyepiece.
28. In the dungeon cupboard (if Hagrid could stash a baby Aragog there, surely you can hide some matzoh).
29. Between pages 394 and 395 in your textbook.
30. In Snape's office.
31. Specifically, in Snape's potions storeroom.
32. Even more specifically, wedged between two of the most foul ingredients you can find in Snape's potions storeroom.
33. Entrusted to Fawkes, though not when he's about to explode, and after you figure out how to stop him from eating the matzoh.
34. Transfigured into an object of your choosing, hidden in plain sight.
35. In the drawer devoted to Fred and George in Mr. Filch's office.
36. Behind the portrait of the Fat Lady, after swearing her to secrecy.
37. Behind any of the portraits, really.
38. Wedged between the pages of Hermione's copy of Hogwarts, A History.
39. Inside a suit of armor.
40. NOT underneath the Whomping Willow because Whomping. Willow. But, in the dirt near the Whomping Willow.
41. In the darkest part of the Restricted Section of the library.
42. In the TriWizard cup from Hogwarts' original victory.
43. Behind the pendulum of the clock in the clock tower.
44. In the cupboard where Lupin stored the boggart.
45. Behind the visor inside Aurthur Weasley's Ford Anglia.
46. In the trunk where Barty Crouch kept Mad-Eye Moody hidden.
47. Under the floorboards of the wooden bridge.
48. Buried in Hagrid's pumpkin patch.
49. Nestled next to the gargoyle outside the Headmaster's office.
50. With the pensieve but not in the pensieve.
51. In the folds of the cloak of invisibility.
52. In the eaves of the roof of one of the greenhouses.
53. Hidden in the deepest pot inside the kitchens.
54. In the stands of the Quidditch field.
55. Hovering in the baskets of the Quidditch field goalposts.
56. Mixed in with the laundry in the Quidditch locker rooms.
57. In the precise spot the Mirror of Erised was stored, after it's moved
58. Under the seat of one of the sailboats that transports everyone to the Hogwarts Express.
59. Folded up in your Hogwarts acceptance letter, tucked under your mattress for safekeeping.