DS6 has questioned Santa and the tooth fairy since he was 4 but not to the point of disbelieving. He asks questions, but he never asks enough to result in NO MORE SANTA. I'm not sure if that's by design or not. We had this conversation a month ago:
Mom: "I wonder what the tooth fairy looks like?"
DS6: "Um, a fairy, Mom. She looks like a fairy. And, you knew fairies are only in fairy tales, right?"
Mom: "Even the tooth fairy?"
DS6: "Well, maybe the tooth fairy is real, or maybe you or dad just sneak in my room after I fall asleep and put $2 under my pillow."
As for Santa, last year he wanted to set up a hidden camera to see if he could catch Santa in action. His assumption was that if Santa is real, he'd see him. So, we set up the camera, and ds went to bed. Dh dressed up in a Santa costume, made noise by the fireplace, and stomped into the room carrying toys back and forth from the fireplace (which was just out of view of the camera). You could see all of Santa from the mouth down, so he never could see the full face to ID dad. He could even see him eating the cookies and drinking milk, but again it was only from the mouth down. He even caught Santa scratching his bum. It was hilarious!
Have you heard of Elf on a Shelf? It's an elf doll that visits each December and hangs around watching kids to see if they are naugty or nice. At night it reports your behavior back to Santa and reappears at a new place in your home each morning. The kids run around looking for it each morning. You can't touch him because it takes away his magic or something like that. Anyway, again, we had to pull out the video camera. Ds videoed the elf disappearing in a flash of light with a loud "magical" noise. Thank goodness for digital editing software. It's awesome. I don't think I've laughed that hard in years. Our friends all showed the video to their kids too, and I think we'll all get a little mileage out of that one. My guess it it helped to extend the believing years by at least a year. I'm not sure we have much longer; Unfortunately, I'd say it's probably our last year. : (
When I was 8, I finally asked my parents if Santa was real, and my dad told me the truth. Interestingly, I was one of only two children in my entire grade who believed any longer. I wouldn't belive the other kids until I heard it from my parents!