My 7 1/2 year old grade skipped 3rd grader has nearly singlehandedly convinced his class that their doubts are ridiculous and that of course Santa is real. He has sold them on the idea that mall Santas are just hired help because the real Santa is too busy supervising the elves to make visits to the mall. We didn't provide him with that explanation, he just concocted it to fit his need and provided it to his class. I've received 3 different emails from parents happy they get another Santa holiday this year!
This is my DS7. He is the one convincing the non-believers. And he is the same with the "mall Santas". My DC get their pictures taken with the Santa from their church every year, so all of their pictures have been with the same Santa. I believe that DS7 still think he is the real Santa (the guy plays it off with the kids at church too... telling them not to tell anyone it's really him in street clothes, etc). I know DD5 does.
DS7 did ask if Santa stops his sleigh on all the roofs or just one on each street. I told him I wasn't sure, and what did he think. He has also asked about what the tooth fairy looked like, and I again, asked him what he thought...
DD5 HATES the tooth fairy. She is terrified of something so small as Tinkerbell coming in and touching anywhere near her pillow.
