Instructions
The First Two Years' Section
Complete each area of the game you can before entering the ̶0;Class Corridor.̶1; You will begin in the ̶0;Potions Subroom̶1; on the west end of the building. From there, you enter the ̶0;Potions Room.̶1; Once you have completed the mission in the ̶0;Potions Room,̶1; you enter the west end of the ̶0;Class Corridor.̶1; There is a door in the north and south corners of this west end of the corridor. To the north, there are six rooms and to the south, there are 18 rooms. Complete the mission in each room.
Locate the Girls' bathroom. It is on the east end of the Hogwarts building off the ̶0;Lavatory Corridor.̶1; If you have not completed the Girls' Bathroom assignment by the Third Year portion of the game, there will be a security troll in the ̶0;Class Corridor̶1; that will be guarding the passage to the ̶0;Main Hall̶1; and you will have to loop around him to make it to the east end of the Hogwarts building.
Follow the ̶0;Class Corridor̶1; to the extreme south-east corner and enter the ̶0;Main Hall̶1;.
Find the ̶0;Foyer̶1; entrance in the south-east corner of the ̶0;Main Hall.̶1;
Walk to the center of the foyer and find the entrance to the ̶0;Lavatory Corridor̶1; on the South wall.
In this ̶0;Lavatory Corridor,̶1; you will see the image of a female wizard above the door of the girls' bathroom. If you try to enter, she will deny you access, after all you are not a girl.
Locate the painting on the wall in the ̶0;Lavatory Corridor̶1; of the Purple Wizard. Pick up the LEGO pieces of the lantern beneath the painting and use the action button to piece them together; you will need this lantern later.
Hold the ̶0;B̶1; button on your Wii remote and zap the Purple Wizard. He will get angry and turn Harry and Ron into girls. This is a temporary and timed spell so hurry over to the girls' bathroom and the female wizard will let you in.
After the Third Year
Go to the center of the ̶0;Class Corridor̶1; and locate the door to the ̶0;East Courtyard̶1; on the south wall. Walk toward the east end of the ̶0;East Courtyard̶1; and locate the door just south of the center of the back wall.
Enter the ̶0;West Courtyard̶1; and walk all the way to the end of the courtyard to the door just north of the center of the back wall and enter the ̶0;Courtyard Corridor.̶1;
Walk to the center of this corridor and look on the north wall for the door that will go up into the ̶0;Main Hall.̶1; This is the only way to evade the Troll Guard in the ̶0;Class Corridor.̶1; Follow the same steps from the ̶0;Main Hall̶1; to the ̶0;Foyer̶1; as explained in the ̶0;First Two Years̶1; section of this article.