Professor Gong is AMAZING. Her lectures are super organized and clear, plus she is absolutely a math genius. She has office hours twice every week and she is super helpful. The class covers mostly sequences, series, derivative and integration. It's a proof-based class, so if you are good at proofs, this class won't be that hard for you. It might be hard at first to understand the material, but as long as you put enough time into thinking, it is a fair class. The tests are fair and Professor Gong gives you the chance to correct some hard problems after the tests. She cares more about how much you've learned in this class, instead of the score you got in one midterm. She doesn't collect homework, but there is a quiz every week. Overall, I highly recommend Professor Gong!!!!

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.