Many times when we discuss keeping our private information private so that we don't fall prey to identity theft or online predators, we fail to point out the importance of protecting our passwords. At every single classroom discussion I've attended, I've heard very sad stories from very young children about having their passwords stolen. And you'll be amazed at who is doing the stealing!
Even if it's just their Club Penguin password, children find it very unsettling to have their games changed, points removed, accounts wiped out. And when your password is stolen, this is very often what happens. How do young children get their passwords stolen? Often, the theft is committed by the people they trust most: siblings and friends.
It can happen at home, when your child briefly gets up from their computer to do something else and their password is changed by a teasing sibling. They are still logged in so they don't even realize what's happened until the next time they go to play and can't get in. Or it happens at school when a neighboring child at another computer just watches what is typed into the login screen and remembers the password for their own use. Or the child allows a friend to have their password in order to share their account. Shared accounts was a phenomenon I hadn't realized had become common but with many child-oriented websites charging monthly fees to play their games, it isn't surprising that parents ask their children to share or that children offer to share with their best buddies.
Remind your children of the risk of sharing a password or inadvertantly letting someone see yours. If they think this might have ever happened to them, sit down and immediately change the password. Make sure the parents have all your children's passwords so you can help them administer their accounts. It's very difficult to get help from the website administrators, especially if, from their end, nothing wrong has occurred.