AUSTIN (KXAN) -- In Texas public schools, your child gets three tries to pass the STAAR test. But we found their teachers get an unlimited number of chances on their own required exams. Like many professions, teachers and principals must pass certain tests to become certified. It's the state's way of ensuring they're qualified for the job. But educators are commonly allowed to work in schools even while they're still trying to become certified. A KXAN investigation found some have failed over and over.