Initially, Ron thought that a student at the meeting had betrayed them (by them, I mean the D.A.), until Hermione pointed out that if they had, she would have known about it due to the jinx she placed on the parchment that they all signed. Despite the ban, Harry assured all the members that the meetings would go ahead once an ideal location was found. They would just need to be careful. Soon, Harry was informed the Room of Requirement by the house-elf Dobby, who occasionally used it to store the drunken house-elf Winky. After Dobby told how to summon the Room to Harry, Hermione, and Ron, the D.A. convened for their first practise session.