Okay... so I'm sure you've already seen a lot of the other reviews... BUT I'll say that most, if not all of those were written before the final exam. Going by what the final looked like, it seems that he's starting to improve based on this criticism so that makes be hopeful for future classes. It kinda hurt to see all these negative things being said about him because he really does seem like a genuinely nice person. As a teacher though, I'd say a fair amount of that criticism is warranted. But of course, this was his very first class ever, and we can't expect him to be perfect right off the bat.

Look, I didn't really have a good time in this class, I'll be honest. But I also don't think getting a class with Barr is a death sentence. He can only improve from here, so I sure hope whoever's reading this in the future will have a better time than I did.

This class was rough...throughout the entire quarter I honestly felt like I was failing because the midterms were so applied (like verging on bio tests applies). The biggest problem is that Prof Barr doesn't give answer keys to problem sets, so you have no way of knowing if what you're doing is right. I did pretty badly on Midterm 1, which ended up being dropped for the final. The final was actually way easier than the midterms, so hopefully he's learned that his super applied tests aren't the way to go. Homework is a large part of the grade though, which is easy to get 100% on. And he does offer extra credit. So our grades ended up being ok in the end, but the journey was rough and I'm so happy to be done with this class.

If there is any other option, take the other option. If you can delay taking this class until another professor besides Barr offers it, do that. If there is another professor, take the class with that other professor. If you're thinking of switching to a different major, and that major just so happens to not require taking Chem20B, this is your sign to switch your major. Please. For your own sake.

Lectures: Most lectures are generally okay. He gives a lot of examples, which is nice to get a sense of using conceptual topics. He's also poor at time management, so some lectures would be 35 minutes on one example and 15 minutes on 5 extremely conceptual slides. Does not record most of it.

Office Hour: Typical for a 600 person class. Anywhere between 50 to 200 people attend. However, he spends a long time answering each question such that only 3 or 4 questions at most are answered per hour. He also talks about things related to exam questions which he does not mention in lecture.

Homework and Discussion: OWL is actually quite helpful considering the readings assigned is extremely difficult to understand. Group component of the homework is really effective if you have a good group. I got lucky so had a good time.

Problem sets: potentially very helpful, but given that he does not offer an answer key, it's difficult to justify the time to do the problems and wait at office hour.

Exams: midterm exam questions focuses heavily on application and have very thin connections with lecture material. Requires some degree of outside knowledge (what he calls "intuition") to do. Final questions are more fair.

Overall: If you already know some chemistry or remember AP Chem topics, then this would be fairly okay. If chemistry is not your strong suit and you don't like chemistry, then find a friend who knows what they're doing.

Corbin of chemistry. Go check corbin's reviews that will give you a clearer idea.

While I did disagree with some of Barr's policies like not giving answer keys and not recording the parts of the lectures with examples (although I think he's stopped doing this), I have hope that those parts of his teaching style will improve because this was his first quarter. I understand where a lot of these reviews are coming from because while you're in the midst of this class it feels bad. I don't know how else to put it. The tests feel impossible, the discussion section problems ask about things you haven't gotten to in lecture yet, assignments are coming from like 5 different sources, and you never know if you're doing anything correctly. But looking back, the tests were tough, but fair with his grading scheme and the final was very straightforward. I didn't particularly enjoy this class, or Barr's teaching, but it's certainly not as horrible as some of these reviews indicate. Oh and the textbook is like reading a whole encyclopedia. Don't bother, just use chemlibre or google things.

To be fair, I struggled a lot during the quarter for this class. Barr is a nice professor, but his midterms were difficult and often involve a small portion of irrelevant stuff, however the difficult questions were discussed during lectures beforehand. The homeworks are pretty straightforward, and if you pay some effort getting 80%(full credit) is just a piece of cake. OWLv2 is very easy, and even if you're bad at chem you can still finish them. I wanted to give Barr a low rating after midterm 2, where I just sat in my room not knowing how to do his questions. However, if you attend 8 discussions, your lowest midterm score will be replaced by the final exam. He used absolute grading, where 87%+ guarantees A-, 77% guarantees B- and so. Honestly I never expect that I can get anything above B+ before the finals, but turns out his final is pretty easy and straightforward. Overall speaking, give this man some time, he's good but what he needs is some time. Would not specifically recommend Barr, but he's worth a try if there's no decent (>4.0 bruinwalk rating) professors available.

While I understand teaching a course for the first time is difficult, I feel that Professor Barr taught with the intention of serving his own preferences rather than helping students succeed. The majority of students (including myself) felt let down by Professor Barr’s unfair policies and refusal to adapt to students’ needs. He stresses empathizing with his students, but did not meaningfully address any student concerns throughout the entire course. The most alarming issues are his lack of communication and transparency on many levels.
First, there are no answer keys to the practice problem sets. The professor justified this policy by saying it would increase collaboration among students, but we didn’t even know whether we were doing the problems correctly. When the class asked him to make answer keys available, he basically just brushed our requests off by saying he or the TA’s could answer our questions so there wasn’t a need for keys. That said, I went to multiple TA’s office hours and they all gave different answers to the same problem. This is not surprising since there was no key. I went to his office hours hoping I could get some clarity, but it was extremely hectic and I never got my questions answered. The professor offered vague explanations, and I left more confused than I arrived.
Second, there were many substantial issues with the first midterm. The professor set unrealistic expectations prior to, during, and after the exam. The exam was set for a Friday from 5-7 pm, and the last of the material that we had to know was covered the morning of. Although many international students put in requests to take the exam at a different time, he ultimately decided that everyone had to take it on Zoom during the selected exam time. This means that some students were going to class in the late evening then taking the exam hours later in the middle of the night. His justification for this was that the department strongly discouraged him to give 24 hour exams (even though most of the other professors in the department gave 24 hour exams…) and that since the date and time of the midterm were listed on the syllabus, it was the students’ responsibility to properly adjust for the time-zone issue. Talk about not catering to virtual learning during a pandemic.
Leading up to the midterm, the professor mentioned multiple times that the midterm was going to be easier than the homework and the practice problem sets. On the contrary, it was much more challenging. Personally, I felt agitated not with the midterm itself, but with the fact that he set up false expectations about the level of difficulty. The test also had a few wording issues that were only vaguely addressed, leading to even more confusion. It was hard to ask questions during the exam because there was only the professor and one TA proctoring several hundred students, so a lot of questions went unanswered. Furthermore, the time was extremely tight so many students felt rushed throughout the entire exam.
After the exam, the professor gave us an estimated time of one week before grades were released. He would tell us they would be done on a certain day, then keep pushing back the date. The individual exams were released over two weeks after we took the exam. The group portion was returned to us a week after we finished finals. I understand that grading exams takes a while, but he caused unnecessary stress by telling us they were almost done being graded when they weren’t. There were also some parts of the exam grading rubric that were concerning. For example, students got marked off for having the correct answer in different units even though he never specified which units he wanted. While this was not an issue for most of the questions, these ambiguities resulted in lost points which could add up. He capped us at 3 regrade requests per exam, with required written explanations for each request. He was extremely picky when giving back points so most of the requests were denied or only partially granted. There are no regrades allowed for the group exam. Additionally, the professor decided to slightly alter the rubric after the fact so many students were losing points on the group exam that they had earned on the individual exam. Needless to say, the whole entire midterm from beginning to end was basically a disaster.
In preparation for the second midterm, he made a few changes to his lectures and to the exam policy. He started integrating more practice problems into lectures, announced that the second midterm would have one less problem, and mentioned that 2 TA’s would proctor the exam with him to speed up answering questions during the exam. I was feeling very optimistic that this exam was going to run more smoothly. Well it turns out, none of those changes mattered. Although there was technically one less question, the exam felt even more rushed because of how difficult and confusing it was. 75% of the exam was challenging material we barely skimmed over or didn’t cover at all. Additionally, most of the problems involved unfamiliar topics that required loads of background information and only loosely related to the class material. The test was poorly worded and not representative of what we were learning in class for those past few weeks. As a result, students had lots of questions and most went unanswered because the TA’s couldn’t keep up with so many questions coming in.
It is not surprising that many students felt defeated by the grueling exam and lack of support from the professor. The professor glossed over our concerns by saying he completed the exam he wrote in less than half the time we were given, and showed it to a colleague who was impressed by the caliber of the exam. He also told us that in a random sample of 10 exams he graded, the average was 76%. Most of us were skeptical since the second midterm felt far worse than the first one (which had an average of 72%), and we were right to be: even with the five points of extra credit and the partial credit on the exam, the average ended up being 68%. The professor told us (after the fact) that he intentionally made these midterms more applied to “stretch” us because we could drop one of the midterms if we attended 8/10 discussion sections and performed better on the final. Last I checked, I wasn’t Elastigirl. The “drop” policy may be helpful, but it doesn’t justify giving unreasonably demanding midterms. While it’s better than nothing, this drop ultimately boils down to your final exam replacing your lowest midterm if you get a higher score, meaning your final is now worth 46% of your grade. It’s not very comforting knowing that your score in the class depends on one exam worth almost half your grade.
Most of us were extremely stressed going into his final exam because we expected it to be similar to his midterms, despite him saying that the final was going to be less applied. However, true to his word (for the first time this quarter), the final exam was more straightforward and related to the course material. There was a relatively heavy emphasis on special topics (accounting for 16% of all of the points) that we only spent two lectures on, but the questions were simple enough and fair game.
Waiting for grades was very stressful because we weren’t allowed to ask for regrades on the final and didn’t know the cutoffs of + and - for each letter grade. Our grades were completed on the last possible day even though he’d promised them sooner. He may have graded more leniently on the final exam because most of us got better grades than we expected.
Ultimately, even though our grade distribution was better than expected, I would never want any student to be subjected to the unnecessary amount of stress Professor Barr caused while teaching this course. While I don’t doubt his passion for science or teaching, there are many improvements that need to be made to his erratic teaching style before I would recommend any course he teaches.

Barr's class was very strange. He seems like a really nice guy, and it was his first quarter, so I'm pretty confident he'll be a better instructor in future terms. I think he really wants us to love chemistry. His homework problems are very in-depth, his midterms were extremely nuanced and difficult, and his class is structured such that students in office hours have a huge advantage. I didn't really want to commit this much time to chem every week, especially after being told 20B would be easier than 20A and more like AP chem. I was pretty unprepared for the level of material in this class, and I consistently felt like I was lacking a basic understanding of the material, which I needed to succeed. Barr's midterms were insanely difficult. I probably studied 20 hours for them (which is much more than I usually study) and barely passed one of them and didn't pass the other. Barr confidently doesn't curve, and this is pretty frustrating when it seems like at least half the class is failing. But somehow the final helped us all get good grades?? My guess is he ended up curving because I would've had to get like an 86 on the final for an A and I managed one even though my final grade was a 70-something. The final was very reasonable. It reflected the lecture material and was relatively straight-forward. I was very impressed with the lack of trick-questions as opposed to the midterms. However, this does not mean this test was easy. I studied the most I've every studied for tests in this class, which was a bit annoying because of how little the tests reflected the basic understanding of concepts required for the class. Then, there was the homework. There were problem sets every week, which you absolutely cannot do without going to office hours and watching him explain the questions. They're very very difficult, but reflect the midterm difficulty, so to succeed you HAVE TO go to office hours. You really can't get by without it, and the people I know who got As are basically the people who went to office hours. The homework is assigned four times on Friday evenings and due Monday mornings. You have to work in a group (even online), which are assigned in week 2 of discussion. These were really inconvenient if you had different time zones or work shifts and were trying to coordinate over zoom every other weekend. My group was really good though. We're all good friends, so we didn't mind it too much and it helped us succeed. But if you didn't like your group or couldn't make office hours you're kinda fucked. Overall, you'll survive. Do your best on the midterms (16% each), do all the OWLs and surveys and participate in discussion (total 20%), and get >80% on all the homework (will give you full credit, category worth 18%). Then all you have to do is study your ass off for the final (30%), and if you manage to pass it, you'll be guaranteed at least a B. Good luck!

I don't even know where to begin with Professor Barr. At first, I thought he would be a decent Professor, but as time went on that hope vanished overtime before being shattered by the second midterm of his. Thinking further on it, there are three main issues that need to be fixed in this class.

The first encompasses his exams. While there were no problems with the first midterm, the second midterm and final had glaring issues. When I took them, the questions were worded very poorly, and it was hard to determine what I was meant to do. Moreover, the Professor does not answer questions during his exams despite repeatedly saying he would. I recognize that the large class makes it difficult, but it's simply unacceptable to expect students to determine the thought process that he was seeking. Moreover, the Professor conducts a period before each exam where he goes through the questions and "explains" what he's seeking. This period is more than useless and is actively dangerous to listen to. Repeatedly, he would explain that he was looking for something not actually written down, but the answer key that he used to grade would not reflect this.

Secondly, there is no feedback for students. While he does have a grading rubric on Gradescope, which helps somewhat, that's it. He will go over the exam once, and with COVID, I had great difficulty attending live lectures leaving me in the dark. Furthermore, he cuts out portions of his lecture from the recordings, explaining that he wants it as an incentive to attend the lectures. Well, that would be great if it was actually possible for me to do so. Additionally, he has a draconian regrading system that seems like it's meant more to discourage regrades or discussion instead of discovering faults in his grading scheme.

The third and final major fault with this class stems from a fundamental issue of the Professor. No one knew what he wanted us to learn. Discussions comprised a series of practice questions that we would do in groups, the book had some topics, and his lectures would cover the book for the most part, but he would occasionally segue into other topics for 5-10 minutes. Those small tangents appeared on the exams. This was extremely discouraging for me, and my friends and I wondered what was the point of studying, reading the book, or attending discussion if he was going to test on 5-minute topics that we covered once.

All in all, do not take this class if you can avoid it. While Chem 20B might actually be an interesting class with another Professor, this class killed any enjoyment I had of chemistry. I firmly recommend never taking a class with Professor Barr if this is the level of instruction one should expect from his classes. Reading the textbook on your own would both be more entertaining and more helpful that this course was. At least I learnt something from reading it.