Totally normal. I have one child who did things like this all.the.time. It was maddening. I had to remind myself that this wasn't really an act of defiance, but more his exploring, experimenting and trying new things. While he still gets into trouble at home now and then, he understand the boundaries now and don't purposefully do anything destructive. His teachers call him a model student and he's doing great in school.

Our other child was pretty much a perfect angel at that age (it would never occur to him to cut his sheets). He actually now has more of a devious side and gets into more trouble at school.

My 10-year-old DS recently got a haircut that he hated. (Keep in mind, he has Asperger's) I took him to my salon because the wait at the kiddie salon was over an hour. He didn't like the place because there "were no dudes in there." And he thought the stylist cut his hair too short. So when we got home he locked himself in his room and hacked up his hair. I didn't even know he had scissors in there. He often goes into his room when he is angry so I didn't think much about it. He came out with big chunks out of his bangs and the sides. He denied it but I found the hair right on top of the trashcan. School pictures were 2 days later. Ugh.