My 6 yr old would get on the bus every day without his backpack if I didn't put it on his back. Also he loses his glasses many times per week even though he wears them all day until bedtime... How this happens I have no idea. Yesterday I let my kids get a box of lollipops for Halloween and my daughter asked me where the box was and she was holding it in her hands. When kids are that little they think whatever they are thinking about is the most important thing in the world and my kids are probably thinking about things 24/7. I think they are just not super focused on things that are less important to them. Of course if you say something they are not supposed to hear they will remember it for the rest of their lives ha! Hopefully it's just your son being a 6 year old.