Trust me, you have NO IDEA how bad 3's can be. The three-year-old class at my school *shudders*... it's like a teacher's nightmare.
You know how's there's always that one kid who just won't listen and throws insane tantrums all the time? This class has about 10 of them.
I've seriously tried every single trick in the book to try and get them so just settle down for 5 minutes. The only thing that has ever worked was giving them each a silly band if they behaved the whole day.