probably the worst class I've taken at UCLA, Felker did not care about student learning and wasn't super pumped to be teaching

Professor Felker does not teach effectively in the class. His lectures are completely on the blackboard with chalk, no slides and they're hard to see unless you're somewhere near the front. They're pretty ineffective, and straight from the book. It's really hard to pay attention. His tests are completely free response, and super tricky with lots of room for error. I went to Felker's room for office hours and he was extremely rude. Don't take him if you can avoid it, but I'm pretty sure he's one of the only professors that teaches.

Lecture:
Professor Felker is not a great lecturer, and I did not find that going to lectures was very helpful. He does not use lecture slides, so he writes on the chalkboard. He likes to draw diagrams and show derivations that nobody can really follow. Overall, you are better off just reading the textbook and trying to do the OWL problems on your own.
Grade:
Please do yourself a favor and go to the test bank to get some of his previous exams. He often tests on the same concepts as previous years, and it is possible that he will reuse the exact same question with slight modification. The good thing is that he allows you to use a cheat sheet during the exam. For the midterms, you can have 3 pages front and back, and for the final, you can have 5 pages front and back. You should take advantage of this by writing down as many formulas (thermodynamics formulas especially) and some practice problems. The exams would be nearly impossible without looking at previous exams. The exams are mostly calculation based.
Grade Breakdown:
OWL: 20%
Midterm Exams: 40%
Final Exam: 40%

Chem 20B is essentially AP Chemistry. I didn't learn too much new content and it was essentially review most of the time. If you did well in AP Chem you should do well in this class. If you didn't take AP Chem I can't speak to the difficulty of the class but I didn't find the concepts hard.

Lecture:
Felker is a knowledgeable professor but doesn't make his lectures engaging. I had a hard time staying awake in class some days even if I was sitting in the front row. He likes to use the chalkboard but erase with a whiteboard eraser which I found hilarious. He brings prepared notes with him and goes over his concepts and usually does a lot of examples in class. It goes pretty fast and he commentates while he's writing. I don't know how well I would have done if I hadn't taken AP Chem because most of the concepts were familiar.

Homework:

Felker uses OWL which you're likely familiar with from 20A. It's an online program that asks questions related to the content in class and it takes a couple hours. Most of the homework helped with understanding some of the difficult concepts but sometimes it can be frustrating when you have to be specific with decimals or the program's answer is incorrect.

Discussion:
The discussions for this class were odd because the TA would never actually review the material for you. They were instructed to only answer your questions and if you didn't have any questions you'd just sit there doing nothing. The best way to use this time was to do the OWL before discussion to prepare questions or ask questions about concepts from lecture. Most people don't have any questions so you could have the TA answer all your questions the entire time.

Tests:
On the midterms you're allowed to bring 3 separate pieces of paper with formulas or chapter questions or whatever you think will be most helpful for the test. I just wrote down all the formulas from the book and class and that worked well. On the final, you're allowed 5 pieces of paper so you'll have to get rid of one but I didn't use 3 full pages for the midterms so I just added the later material onto my cheat sheets.

The midterms are relatively straightforward and it was entirely possible to ace the entire thing. The formula sheets bring up the average by a lot and if you want to do well you have to get almost every question correct. The best way to prepare for the midterms was to go over old tests from the test bank and look at the end of chapter questions.

The distributions for the exams were as follows:

The median score is 75, std dev is 17, high score is 100, and low score is 17.

Midterm 2

The median score is 70 and the std dev is 20. High score is 100.

The final distribution wasn't released

If you're hesitant about taking Felker I can say that he'll teach you chemistry just not in the most engaging way. I read the book alongside the lecture and found that was helpful. I wouldn't go out of my way to avoid him if it's a good lecture time, but that decision is entirely up to you.

The material of 20B is much more similar to AP Chemistry material than 20A. Having a background in chemistry is important when taking Felker because he doesn't help much with understanding it. His lectures are straight-forward: boring, but lectures out of the textbook. Homework is textbook-based on an overpriced OWL website. The tests were fairly difficult considering he did not prepare us for the caliber of application of material learned. If he gave practice problems at the level he expected of us, the tests might have been more doable, but those tests were pretty hard. Especially the final. On the bright side, he allowed 3 pages of notes, front and back, for the tests, so at that point, I took notes and equations from the textbook for 2 pages and filled the last page with practice problems. I would not recommend taking Felker, but if you must, it is doable, just not the greatest experience.

Felker is very boring but go to lectures and try your best to stay awake. Sometimes he provide information and equations that show up on final exams or the midterms.

Don't be terrified when you know you would be taking Felker, he's not that bad; he's just mean. Office hours: you don't need to go cause he's kinda mean. Ask questions via email. He's helpful and straightforward in emails and he doesn't get annoyed at you because he don't have to see your face. Trust me I think he just hate seeing humans in his office in general. His office his not welcoming and he's always grumpy.

MOST IMPORTANT:
Get those practice papers ASAP: guarantee at least 1 question from previous exams would show up.
Do the additional problems, guarantee showing up as well.
Just do a lot of practice when it comes to thermo. Make sure you know how to deal with the equations and when do you use each.
Use the cheat sheet well, fill them up with previous questions and useful equations. The smarter you use the cheat sheet the better your grades. He provides barely anything other than numbers.

Professor Felker is not a good lecturer; he speaks on topics in lecture that will probably not appear on the midterms/final, and many of the things he writes on the board are confusing. You'll probably learn more by reading the textbook and doing OWL (online HW) problems. The one good thing about this class is that the exams were pretty fair. He tends to use problems from old exams while also making a few new ones that reflect the topics he covered in lecture. Overall, I wouldn't recommend Felker, but if he's your only option, the class is definitely doable if you study well.

Professor Felker was the worst professor I've had here at UCLA. He did not explain the material, he simply wrote equations and answers on the board, and expected you to understand the concepts. Midterm 1 was fair, Midterm 2 was terrible, and I can't say that much about the Final, but considering I got an F in the class, I'm assuming it wasn't too good. The OWL homework assignments were time consuming and not helpful in preparation for the exams. They were only "easy" because you got six attempts and it was a matter of getting it wrong the first time and plugging in new numbers to the given solution the second time around. Professor Felker is also an extremely dry lecturer who doesn't bring energy or enthusiasm to his lectures. Like most other reviews, you probably don't have a choice but to take Felker if you're reading this, but if you have the chance, put off CHEM 20B a quarter and get ANY other professor that isn't Felker.

Honestly, the way to pass this class is to go to the test bank and study past exams. That's the only way how I knew how to do any problems on the midterms and the final, since Felker is definitely not a great lecturer. Talking at a chalkboard and rambling on might be acceptable for a class of twenty people but not for hundreds of people. The first midterm wasn't bad, but the second midterm was pretty weird, which was evident by the distribution: the average was 70, but the standard deviation was 20. The final was alright as well, but as long as you have the right material on your cheat sheets, the tests are all doable. Don't expect an amazing curve though, since there are always people who get perfect scores.

I did not learn anything from professor Felker. His lecture style is incredibly boring, uses no slides so there isn't any material to look back upon. Not only that, he rambles, places emphasis on words that have no meaning (such as conjunctions when speaking) and thus the textbook is basically gold. I have seen people doing other classes' homework in his lectures since he is so boring and yet for a professor that lectures heavily on derivation and understanding, Felker's tests are 100% math based. If you're looking at this, most likely you will have to take him anyway as there aren't many options and the chemistry department in UCLA isn't that great either. Basically, read all the textbook, making sure to understand all the formulas and you should be fine. I wouldn't take him ever again though.