Have you ever been intimidated by (male) students yelling at you? I am female. Many years ago, when I was a younger, less experienced professor, I would return tests and answer questions immediately. One day a man who was taller than me (most people are), shoved his paper exam in my face and proceeded to tell me I was wrong and that "I didn't know anything". He did poorly on the exam and was instantly angry with me for his grade. I looked at the exam and showed him why he was wrong and he grudgingly walked away.
I recently heard from a non-white female colleague who recently was working with a male student who became very angry because he got a problem incorrect. She told him he was wrong and he responded with, "You don't know anything"! It was about significant figures, and you guessed it, the addition/subtraction rule. And another time I had a female student it in my office while I carefully worked with her through a difficult problem, and when we were done, she asked my male officemate if I was right. This happens in more subtle ways over and over.
I understand that this is not the students fault entirely; it is a generational bias that I believe is changing, ever so slowly. Over the years, I experienced more of this bias in the classroom so I developed several "policies" to help prevent this scenario from happening again. These help me deal with those students, male and female, who think because I am a female, I cannot possibly be a good scientist. If a student has confidence in their ability, then they will be less likely to want to fight, and more likely to respect you.
How to build confidence along with competence in your students:
1. Do not tell students they are wrong. Allow them to discover the correct answer for themselves. For sig figs as an example, I tell students that I will not answer their questions in office hours or in Zoom unless they take the time to copy all the "rules" to their notebook or a note card and show them to me.
2. I allow them to work out the problem in front of me, and when they need to apply the sig fig rules, I "allow" them to use their notes to apply the rule correctly. 100% of the time they say, "Oh, now I get it".
3. Encourage students to make note cards (not "flash cards") for significant figures, and other things like polyatomic ions, naming rules, Lewis/VSEPR hints, then show them how to use the rules every time.
4. No memorization even on exams. If they have the note cards (or clear notes in their notebooks) and they use them every time during the learning process, they will use them efficiently on the exam and there is no need to cheat to look up answers. Their confidence will rise and they will share this with classmates. I usually start with, "Unless you have a photographic memory..." do not memorize. I remember my first year of teaching, and I could not list the guidelines for naming organic compounds. I know how to name organic compounds because I worked in the field and learned by repetition. I learn by repetition. When I had to teach this, I made a list and followed it for the first three years until I didn't have to anymore. Until my confidence grew. One example I use is that pilots do a checklist before takeoff; they do not memorize the list. They have a list and check off each item.
5. I do not accept exam questions until students have had 24 hours to review their exams. I suggest that they redo the exam at home, using all their notes in a less stressful environment. I also give them the link to my "How to get an A" document. Then after the 24-hour "reflection time", they can ask me any question and I work it through with them. (See #1).
6. Encourage students to make a handwritten glossary of chemistry words. Give them examples of why this is important. Precipitation has a vernacular definition and a different meaning in chemistry. How many other words do you use every day because you are fluent in chemistry that may not be a common term to your first time students? This can be particularly helpful for students whose native language is not English. But if you encourage all students to make a glossary, then you are helping all not just a few.
I hope that someday, when my 6-month-old granddaughter is an adult, standing in front of a diverse group of people for any reason, that she is judged by her knowledge and not because she is female or non-white.