Reframe the Purpose of Assignments
Stereotype threat can be triggered when a test or task is presented as being diagnostic of the stereotyped trait, like intellectual ability. If possible, reframe the tasks you have your students engaged in as something else: a self-exploration exercise, a group endeavor, an expression of what they value. Of course, you are teaching a class, and you probably have to give out grades, so it may be difficult, or even undesirable, to frame every test as non-diagnostic. When this is the case, remember that you can reframe what the task is diagnostic of. In particular, you may consider reframing the exam as diagnostic of how much material or method a student has absorbed rather than intellectual or philosophical ability. Recall that it is good to encourage students to see intelligence as learned and malleable. Your students may come into the classroom thinking that intelligence or philosophical aptitude are innate, but you should remind them than anyone can succeed in your course.
Assure Students that the Course/Exams Show no Difference that Tracks Identity
Simply assuring students that a test does not show differences based on race or gender can reduce stereotype threat. You may considering adding a statement to the beginning of each exam indicating that the exam has been gender and race (and any other identity category you are concerned about in your classroom context) fair in the past. You may also consider adding a general disclaimer to this effect to your syllabus.
During Times of Assessment Remind Students of Positive Role Models
You may not always be able to alleviate stereotype threat through the above two interventions. Another way to try is by reminding your students of role models who share the triggering social identity, but who have found success in the tested domain. One way social scientists have been able to do this is by having a test administered by, e.g., a Black examiner who is described as competent in the tested skill. While you cannot change your own identity to serve as a role model for all of your students, you could introduce role models in others ways, like having diverse teaching assistants or proctors.