Stereotype threat is when a person feels like they won't be able to do something because of how people expect them to do it. For example, if a girl was taking a test in math and her teacher, friends, or family all thought girls weren't good at math, she might start to worry that she won't do well on the test and this might make it harder for her to do well. Stereotype threat can happen to anyone, but it is especially common for people who are part of a group (like girls in math) that is stereotyped as not being very good at that subject.