My opinion on Barr pretty much aligns with everyone else's. I honestly think that he's a nice guy who cares about teaching, which automatically makes him better than a lot of other professors, but he's just so new and it takes time to iron out a teaching and test writing style that works. There is a lot of mandatory group work, and I got very lucky with an excellent group so that ended up helping me a lot, but it's all up to chance and I understand how people could be mad about that. I actually felt that the workload of the course was pretty light, with only 4 homework assignments due in the quarter graded by accuracy and weekly pre-lecture activities that hold your hand the whole way through. The two midterms felt like the extra challenge problems at the back of a textbook that no one likes, just too detached from the material to feel fair. I felt like the final was a very big improvement over the midterms (probably due to people complaining in his emails) with much more straightforward questions, and if you scored better on the final than one of your midterms then he counted your final score twice instead of that midterm, which was cool. I feel like all of these negative reviews will be kinda pointless in like a year as I think he will improve very much, but if there are other professor options with good reviews then I can't recommend Professor Barr over them in good conscience.

I told myself that I would wait until I was done with the class to really make sure that what I was saying reflected the class as a whole.

As you've heard, this class, for all intents and purposes, sucks. Do not take it if you have the opportunity. My caveat to most of the other reviews is that this not only was Barr's first year teaching, but he also was given the entire 20B course to handle on his own. I don't think he's the devil in Disney's clothing. I'm pretty sure his ideologies and test styles would have been a little more fruitful if he didn't have the entire 600 student load to work with.

On the other hand, there is a lot of things wrong with the class. The emphasis on group work, especially given the times that we are in now, was a miss. The lying to the students was disappointing. The tests that didn't really mirror content in the class were painful and disheartening. But the worst to me, and many others, was the refusal to listen to our complaints. I understand that he had research on how students work, but there comes a point where if 10s if not 100s of your students are asking for a simple answer document for your problem sets so they can confirm that they are grasping the content correctly as they cannot attend office hours for a multitude of reasons, maybe reconsider. The lectures also left a lot to be desired, as he would spend about half of the hour lecture answering questions that could easily be left to Campuswire, and the other half zooming through content that is sparsely detailed. He would be willing to spend an entire class on a derivation only to reveal that it wasn't content we needed to know but spend only a few minutes on concepts that were entire questions on an exam.

In summary, this class sucked. I wouldn't recommend taking it if you have the opportunity to do literally anything else. But, I think (and hope) that with time and actually listening to the students Barr could do better. It's clear that despite his shortcomings in translating it to the students, he has good knowledge of the content.

Professor was extremely interesting. No doubt he came to class super passionate about something, but honestly that something didn’t seem to be chemistry. He seemed more concerned about bettering his teaching skills than actually teaching. His use of varied resources was nice in theory but annoying in practice. He seemed to be trying to do too much at once, and most noticeable the grading suffered.

Barr tried to reinvent the wheel in a time when the students could have used some familiarity. His grading policy added unnecessary stress on top of a stressful time. Early on he didn’t seem sure about how the grading would work out and tried to pass this off as a normal thing even though he is literally the one who decides. When describing the class he was frequently vague and occasionally told hopefully unintentional lies about how the class would be set up.

He provided resources to support us but the OWL quizzes were essentially a waste of time assigned a point value. His problem sets were key to gaining understanding but his defiant no answer key stance made no sense. Office hours in this class were necessary to tie everything together and the most efficient way to prepare for the exams, since there answers to problems that Barr wrote could be obtained.

The exams were highly tangential. Several concepts on them were ignored in class but highlighted in review sessions meaning that these were essential parts of learning in the class. Midterm 2 was unnecessarily hard and only justified since the Final would replace a worse midterm score.

There was a group component to the section, leading to the possibility of time zone shenanigans. These sections were ok as the problems we did seemed helpful and more in line with the exams. It really depended on how good your overall group was.

Overall, this class wasn’t good for students trying to actually learn chemistry. It seemed highly hostile to those abroad and with time restrictions. Barr was not accommodating but said he was. For students who know the material already and are just looking to advance towards a major, this class will just be a minor annoyance and probably has less REQUIRED work than other chemistry classes. If this isn’t you then it probably isn’t worth taking the class unless you are prepared to go to many office hours or, like me, have no problem trawling the internet for chemistry resources.

TLDR: Not a fun class for those who don’t have a good chemistry understanding but hey, at least the lectures looked pretty.

Lectures:
Barr seems knowledgeable about chemistry, and his lectures might be helpful if you already have a decent knowledge of the course material (maybe if you took AP Chem). If you do not have a working knowledge of what he is talking about, you will probably be left behind. The lectures themselves seemed to make sense, but he often skipped steps, making simplifications when solving problems that he seemed to assume we would understand despite him never really explaining them. Take good notes. Anything helps.

Homework:
The OWL assignments seemed easy enough, and we had more than enough attempts at each problem to get 100% and get a brief understanding of a few topics. However, they were very short assignments and the problems were nowhere near the difficulty of tests. They were helpful for a first look at concepts, but don't use them to study. It won't help.

The Textbook:
If you took 20A, it's the same one. I would use ChemLibre or Organic Chem Tutor instead.

Tests:
DIFFICULT. Study. He writes them himself and they won't be what you expect. The questions are mostly pretty fair if you really understand the material, but there are multiple reach questions per test. For example, stretching the course material to apply it to current topics in biology, theoretical questions about geology, etc. They are also timed with a strict submission period. He also includes material that he teaches on the same day as the test.

How to Study:
Do the problem sets. I wish I would have done them every week when they were released. They are long, but are really the only way to study. Unfortunately, he won't give you an answer key, so you'll have no idea if your hours of work were going in the right direction. Make sure you have some kind of study group to ask about pset questions and try to make a group answer key. Problems at the end of the textbook chapters would probably also be helpful if you have any time to do them after finishing the problem sets. Also, watch Organic Chemistry Tutor on YouTube and use ChemLibre. They explain things a lot better if you need it.

Empathy?:
Barr constantly says that he "empathizes" with students, but he won't do anything to help them. I think this happened in basically every lecture. Most notably, he insisted on only having one time for tests for every lecture and time zone. Like every student in any lecture took the test at the same time. It worked for me, but some of the international students told him that they would have to stay up late to attend the lecture and then wake up at like 5am for the test. He said he was very "empathetic", then proceeded to do absolutely nothing about it, continued to include material from the same day's lecture on tests, and made no effort to find a way to make the timing work better. This kind of thing happened a lot. He seems to want to appear empathetic, but it's not very genuine.

Grading:
You need at least a 68% in the class and a 50% on the final to pass. Your final grade can replace one midterm. That sounds good, but definitely don't count on doing well on the final. The one redeeming factor of this class was that it seemed like tests ended up being a relatively small portion of the final grade. If you get over 50% on all the tests you should get a C. Based on a poll we did in the group chat it seemed like most people passed, so that's good I guess?

Barr is one of the few professors who really seemed to care about his student's learning. He often gave surveys to students to asses how effective his lectures and assignments were and made an honest effort to improve and implement suggestions. In addition, he and his TAs had multiple office hours every day, so if you were ever confused on a topic there was always an opportunity to ask somebody. The midterms were certainly a stretch, with many of the questions requiring you to take what you learned in the class and apply it to a novel situation. This meant that the midterms were much harder, and even if you knew all the material perfectly you could still stumble as you have to apply the materials in new ways. However, to counteract the difficulty the midterms have a group component, allowing you to get many test points by going over the midterm with your group and resubmitting it. The final was much more normal and easier, with straightforward questions that covered the content (and it replaced a midterm score). Discussion sections made you go through questions with your assigned group, which provided good studying material as the questions were similar to test and PSET questions. The way his class is graded is somewhat confusing as he refuses to give a straightforward curve, he instead says that points gained from (rather easy) HW assignments and points from the surveys act as a "curve". I disagree with having the midterms be so difficult, but the final is reasonable and the rest of the class is filled with many opportunities to learn and improve. (NOTE: This was his first class as a professor, he stated multiple times that he was evaluating his course and technique and planning on implementing changes, so his future courses may be different than what we experienced)

Straight to the conclusion, Barr deserves a much better score than 2.3, at least in the Spring quarter. I gave him a 5 (more like a 4.5)
From my experience in the spring, I would recommend him. His lectures are not bad, for him being a funny and engaging lecturer, though he sometimes goes off topic....; He gives a LOT of assignments(many of which are VERY EASY TO MISS, BE CAREFUL), so the workload of this class is heavy, though the good part is that they boost up your grades for them being easy 100s; The tests are difficult for sure, (cuz it's chemistry), but they are on topic and relatable to the class content (a GREAT improvement from winter as I looked at the past tests). Grading is fairly generous and based on a curve. (Class avg for tests in my session are like mid-70s, so an 80+ would probably give you an A unless there are too many prodigies alongside); Group participation does matter, good thing is that this time he lets us pick our own team. And I appreciate him for this because my teammates and LA are GODSEND!! what I dislike about him is that grading for him takes forever, expect more than 3 weeks for each test.....
A big problem about him is that he gave us problem sets as test review materials (not part of the huge workload), but there are no answers (which make the problem set meaningless), you are completely on your own and the only way for help is OH/review sessions which is not enough. luckily my GODSEND LA gave me his solutions and helped me review, so I didn't suffer so much.
20B in general is not as hard as 20A, most of the contents are reviews/expansions from AP Chem topics. If you did well in AP then you should ace this easily, if you didn't then don't worry, there won't be any quantum mechanic shits like that in 20A.
I had friends who took him in winter and I understand all the earlier negative comments about him. There still are many parts of him and his class that I find it struggling, but he actually listens to students' complains and suggestions I have seen those improvements made in spring. Since he is a new prof. so be easy on him, plus he is a very approachable and friendly teacher. For future students, if you find it struggling in his class, write something serious and helpful in Bruinwalk or direct email so he can improve and teach better.

it's true it was hard. I know I failed that final. but honestly, the best part of this class and Professor Barr is the environment he creates. He encourages us a lot and everyone is pretty much working together and struggling together and dad jokes and chemistry puns at the beginning of lectures are always funny. This is the professor's first? class I'm pretty sure and even though the exams are difficult, and class is painful, the social aspect is pretty good too, especially in this online environment. So expect to have a good time but work hard for a good grade. He doesn't curve but also the percentages are kinder.

There are a lot of things wrong with Barr. I think he was very unfair to international students--he gave exams the same day as lectures at an awkward time, and he doesn't tolerate if your Internet goes out. There are a lot of small assignments that can be hard to keep track of (I hate those damn surveys). His lecture style is really annoying because he talks to you like a 5-year-old. His "empathy" for the class is pretty disingenuous (understatement of the year).

Where I disagree with the other reviewers is that the overall difficulty is pretty on-par with a lower-div chem class. In no way am I justifying his exam style/design, but at some point that's just the reality of these classes. So I don't think you should "avoid him at all costs" (especially because he might be teaching it next quarter). Just try to read the textbook as much as possible and be careful if you have extenuating circumstances, because he is very intolerant about them.

We were told one midterm would be dropped. The second midterm was so. much. harder. than the first. And instead of curving the test or offering corrections or SOMETHING to rectify, he simply blamed the difference in the fact that we were all "shocked" because it was the second midterm was in person. I was the type to get an A+ in 20A. This class was difficult to the point where I couldn't even scrape by with a B+. Not that we were told the grade scale. Anything between a 76% and an 88% were "some flavor" of B. So we can't really ask to see our grades, because we have no idea what constitutes a plus or minus grade. He also does not have a place to monitor your grade. He has excel sheets that you can use to estimate your final grade after each midterm, but again, you are only told what "flavor" of grade you are on track for. So you don't know if you are on the verge of dropping or increasing by a letter grade.
He also talks to us like we are high school students. He doesn't seem to realize that most of us have become very good at teaching ourselves things, so doing something like giving solutions would allow us to teach ourselves. He do be gatekeeping.

This class needs to be refurbished. The professor is clearly doing something wrong as shown by the reviews. In addition, he asks for feedback but I doubt he will make any serious changes such as releasing the problem sets, and overall being more clear when asking questions on exams. Therefore, I recommend you avoid this class unless you must absolutely take this nightmare class.