shy bearded dragon?

Question
I have a bearded dragon. I got him as a class pet for my 4th graders. I bought him as a baby. For the first little while he was very friendly. He would come to the glass and would often be out in his tank where the kids could see him. In the past month or so we have noticed that he is very skiddish, if the kids walk in the room he runs and hides inside his rock. He spends most of the day inside his rock. When I bought him I was told that they are very friendly, however, he has seemed very timid of people. I'm wondering if that is normal or if there might be something else going on...I have also noticed his appetite to have decreased in recent weeks as well. I know they get lethargic when they shed, but he has been like this for a while, and I haven't found any skin in his tank to suggest he has been shedding. Thanks!

Answer
Hello Sam,

Do you have any pictures of him?
Do you take him home on the weekends so he gets attention during that time?

What type & brand of UVB do you have, is it a tube bulb or a compact/coil light?  What type of basking light are you using, is it a bright white light?
Do you give him calcium supplementation on a regular basis also?

They can sometimes get a little skittish when around a lot of people.  Are the kids good with him & avoid banging on his tank, correct?  
It is not normal though for them to be quite to timid, no.  It sounds like something is going on or something is scaring him, etc.  Has anything in the room changed or is he by a window?

Tracie