Horrible Harry in Room 2B is a good book to introduce making smart decisions. I would incorporate this book in my 3rd grade class during the first week of school. Following an integrated lesson on rules and appropriate behavior, we would read what it is like to have a friend that doesn't always make the right decisions. I would make sure that they know not to unfriend them, but instead, to encourage positive behavior and decisions. I would also remind them to always be nice and make the smartest decisions, always.