Elf of the Shelf

Have you heard of Elf on the Shelf? It's a book and small elf that flys to Santa every night to tell him if you been naugty or nice. I am kinda wondering if I should have got it for her. I spent 3 hours explaining and answering questions like:

• Can he fly at night?
• Is he scared of the dark?
• Can he lock the door when he leaves and comes back?
• Has he left yet?
• What time does he come back?
• Why does he only talk to Santa?
• What should we name him?
• and on and on and on.......