We know this because every two years, the federal government asks thousands of teenagers dozens of questions about whether they are all right. Since , it has sent something called the Youth Risk Behavior Surveillance Survey to more than 10, high school students every other year, to inquire about all sorts of bad behaviors that range from drug use to unprotected sex to fighting at school. They smoke less, drink less, and have sex less than the previous generation. This is different from what adults typically expect. One study , for example, asked Americans whether the teen pregnancy rate had gone up, down, or stayed the same since Half of respondents said it was going up, and another 18 percent said it was the same.