I took AP Calculus in high school, and I feel like that's the only reason I didn't get a B- or C+. Professor Gong is extremely nice, but as it was her first ever class at UCLA in Fall 2018, she really didn't explain the concepts that clear. The very first lecture I could tell that the class was going to be a struggle for anyone who hasn't had previous calculus knowledge, because she went straight into the core of Math 31A like she expected everyone to know the basics (ex: limits, derivatives, etc.), which a lot of people in that class hadn't learned. She also brushed over the theories and formulas but didn't went over the concepts thoroughly at all. Even though I've already learned a lot of the stuff, I often found myself getting confused at her explanations of some of the concepts. All in all, great person, super nice, wasn't really a good explainer, would not take her class again because I need to really fully understand the concepts to be able to do the problems, but if you're good with just learning the theory and have no trouble understand math, go ahead and take her.

Sherry cares a lot for her students. I enjoy going to her class because I like seeing how happy she is teaching us. I would definitely take her class again if I had the chance.
Some people talked about how her finals are hard. I didn't really get to experience that in person; not because I thought her finals were easy but because Winter quarter of 2020 is pretty much messed up by the coronavirus. For my finals, we were allowed to collaborate with other classmates, and it is even highly encouraged by the professor. I would say, if the coronavirus didn't happen and I took the finals like normal, I would probably consider the final as difficult. It is really different from her midterms but not CRAZY hard either.
Anyways, Sherry is great. Go to her office hours because now I regret not getting to know Sherry more.

Professor Sherry Gong is the closest thing to a perfect professor you can ask for. She made a relatively difficult class way easier to understand while not sacrificing the fundamental concepts. She tries very hard to make sure the class really understands what she is teaching by taking questions and never turning down a question because it's "obvious". Her exams are pretty easy but she does spend a considerable amount of effort curating the extra credit problems.

I had to take the final amid a viral pandemic and she sent out so many emails reassuring us that we will do fine through the final and answered the tsunami of emails flooding to her in due time. I don't think I've ever seen a professor work so hard for their students. I've heard horror stories from my other friends taking other professors that made me really appreciate what a great professor I had.