The class structure is the main thing that is annoying with this class. Barr himself is okay, the lectures are just okay. You should definitely read the textbook because the lectures alone will not be enough. Also, the tests are very difficult compared to some of the problems he gives you. However, the grading is sorta lenient while also being sorta confusing.

The class is essentially one OWL HW section per chapter, ungraded discussion worksheets, and the occasional group HW. There are two midterms and a final. The OWL HW is fine and easy. The ungraded discussion worksheets are participation based so that is also fine. The group HW can be annoying, but if you get a good group you should be fine. Luckily everyone in my group was in the US so we only had at most a 3 hour gap between us, but if you are international, scheduling meetups to do the HW is going to be annoying. Also for international students, there is only one exam time. You have to show up, regardless of time cause Barr didn't create a separate exam for a different time slot. You need to be on Zoom during the tests, because that's how you're supposed to ask questions about the test and it is where any updates will be given. The tests are very difficult. You'll cover a lot of chapters. Most of the time, we were doing the chapter's OWL section a week before it was actually covered in class.

The worst part was the structure, especially online. In the class there is an expectation that you meet up and work with other people since the weekly practice problem sets, one of the only study materials, has no answer keys. You need to go to office hours to get them, which is pretty annoying. Also, it was hard to find the motivation to either go to OH or set up meetings with classmates since it was online. Additionally, the whole Zoom meeting during the tests was pretty useless. On the first midterm, we got an extra 10 minutes but it was only announced in the chat, so plenty of people missed it.

So if you take this class, be prepared for a difficult course with a high workload if you want understanding of the content and difficult tests that have little plug and chug. Barr is okay enough, but the way that the course is designed isn't great. Especially if you dislike chemistry, be ready to not do that well. The class requires a lot of work, you can't skate by with just lectures and HW.

At the beginning of the quarter, Barr seemed to be an understanding and lenient professor. As the quarter went on, this quickly proved to not be the case. He constantly spews about how "empathetic" and "understanding" he is about being a student, especially since he just finished his PhD, yet then immediately turns around does the exact opposite of everything he claims. There are no alternate exam times, so all international students get is a crappy night's sleep and a half-assed "I'll factor this into the final grade" from Barr. The way he defended himself made it seem like it was a departmental policy to host live exams, yet the previous quarter with Felker proved this was clearly not the case as Felker even provided alternate times, so the only possible conclusion is that this was purely Barr's decision. Additionally, discussion sections are mandatory, screwing over international students even further if they don't get a good time during the rat-race that is UCLA course registration.

Besides lack of consideration for internationals, Barr institutes a load of arbitrary rules that only serve as obstacles to student learning. During discussion, we are forced to make groups to work on worksheets, homework, group exams, etc. However, Barr insisted that the groups be capped at 3 people and would forcibly break apart groups of 4 or more, despite this being completely online anyways. We are college students, not toddlers, which is why I do not see the point of mandatory group assignments especially on a Zoom environment. Fortunately, I landed a good group and we were able to get along well, but for those who preferred to work alone or got a poor group, they were stuck for the entire quarter.

Barr gives students loads of seemingly useful resources in the form of additional textbook problems, OWL reading quizzes, optional problem sets, all that were supposed to mimick his exams and homeworks: only half of that is true. Homework sheets were pulled from the problem sets, but exam questions were tangentially related at best. But, Barr claims that because his exam questions come from the Psets, he will not give answer keys! As a result, if you did decide to do the psets, the only way to check your work would be to match answers with other students, or go in for office hours. Regarding office hours, you can either go in for Barr's personal ones, where he would spend 40 minutes using his "socratic method", which you can read as "basically not answering the question". Or, you can do a TA's, but they aren't given answer keys either, and I have had times when the TA told us "yeah I'm not sure about this either." It took 7 weeks and loads of student (and probably TA) outrage before Barr finally relented and gave keys to the TAs, but sometimes they would be incomplete! This happened for the final psets leading up to finals week. You can imagine the frustration.

Lectures were moderately useful? He doesn't spend a lot of time on concepts, so hopefully you can get through the walls of dense that is Oxtoby, but his explanations are clear and he builds time for questions. The example problems he does are the only parts worth listening to. Originally he tried to do derivations, but those were often poorly motivated and a complete abuse of notation (for the more mathematically-minded folks). I guess he realized the derivations weren't helpful since he stopped after the first midterm.

There's quite a few gimme points which is probably the only reason I ended up with a passable grade. The only note is that you need to keep on top of all his surveys, reading quizzes, etc to really get the most out of them.

Lastly, grading, arguably one of the most important aspects of a course for students. Our midterms had two components: individual and group. Barr told us at the beginning of the quarter to allow for a week to grade. Our first group midterm (worth 20% of the midterm 1 grade) was ungraded even after we had taken the final. That is 7 weeks worth of waiting. By week 8-9, most students still didn't know what their grade would look like, but the pass/fail deadline was quickly approaching. Students had to decide between literally gambling with a passable letter grade or to just completely forsake the class grade. Besides taking a load of time to grade, the graders often made mistakes and would take off points for answers that were clearly correct. It was a common occurrence for students to receive 0 points as if they left an answer blank, when the (correct!) answer was clearly on the sheet. This would typically lead to a regrade, but Barr decided to institute the arbitrary rule that students would only be permitted 3 regrades, and if all of them were rejected, then you would lose that privilege for the entire quarter. And the regrades had to be worth a certain amount of points for them to be even considered. At best, the questions can be described as a "tossup" since they would ask concepts from mRNA vaccines to tire pressure to self-assembling microlayers.

I really hope Barr fixes his class as time goes on, because my quarter was a mess. For those of you thinking about taking Barr: run. Felker would arguably be better since at least he lectures on material and gives homework with problems actually reflective of the exams.

I have never been so worried about not passing a class till I took 20B with Barr. After having Felker I was so ready for a new professor who would actually teach me chem. Well, I quickly realized that wasn't the case. I would go to lectures feelings completely overwhelmed and lost (which was mostly because I suck at chem.) He kinda goes his own way with certain topics like entropy he says "I know most people say it is disorder but I don't like that so that's not what it means." Which was the easiest way to understand such a conceptual term. To understand any of what he was doing, I rewatched lectures over and over again and used youtube, chemlibre and a million other resources. Also, I tried going to OH but he calls on random students which stressed me out so much because I was usually clueless. The problem sets didn't have an answer key so they seemed pointless to do. OWL was also a waste of time. Also, he has us put into groups of three-four to do homework sets which were ONLY assigned during the weekend (6pm Friday to 10am Monday) and all my group members as well as me worked weekends so it was extremely difficult finding time to meet. The midterms were beasts. He also promised us we would have our grades back within a week and we didn't get the final midterm 1 grade back till 2 days before grades were due for the quarter. We never knew how well or bad we were doing because of this and there was no curve but everyone claims to have done wayyy better than anticipated. I ended up switching to P/NP after he told us we HAD to get at least a 50% on the final and judging on my midterm grades this seemed more daunting than it should have been. I know Barr meant well but at the end of the day just avoid him unless he fixes the many mistakes.

Professor Barr is a very nice man. I would enjoy spending time and just talking to him. As a teacher? That's a different story. KEEP IN MIND this was his first quarter teaching ever so he will probably improve.

I feel like his expectations of us were unfair. He expected us to be chemists when quite a few of us were engineering students who will never need chemistry again. His tests were difficult but not impossible, but he did not prepare us for them. Before the first midterm we expected his tests to be relatively easy because he said they would be similar to the homework (which was easy) and boy were we wrong. On the second midterm I did much better just because I knew his testing style and could study and adapt for it. I think if you study hard you'll be okay.

Barr would also answer questions with "it depends" or "sometimes" and generally refused to give straight answers to any questions because "there is always a time where always doesn't hold" or something along those lines and it was incredibly frustrating, but if you ask the TAs and LAs they will give you a real answer.

Most of my complaints with Barr are things that I assume he will fix for his future classes and I'm sure you can read about them in the other reviews (slow grading, having to do multiple chapters per week, expectations that we could go to every office hour, not giving us the answers to the problem sets, etc). He was very engaging and cares a lot about his students, but everyone could tell that he was new and overwhelmed.

I think if you have to take Barr he will not be the worst, but if you have the option of a different professor with better ratings I would go that route.

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.

Once final grades were posted, my opinion on Barr changed a little. The whole quarter, he seemed to be almost ruling with an iron fist and grading quite stringently, but I think he curved the final grades. He kept telling us that there would be no curve, but I got an A, when it was almost mathematically impossible to get an A in the class unless I aced the final, and we are all unsure about our grades from the final exam because he might not give them to us. So, if he actually did a secret curve, this class wasn't too bad.
The class is broken down into OWL, Homework, Discussion, Midterms, and a Final. Basically, the OWL and Discussion is a free 20% of your grade, and most of the homework is free too, which is another 18%. The first midterm wasn't bad, but he had a trick question that messed me up, and he does not believe in grading with propagation of error, so since I read the initial problem wrong, I essentially lost all points for the problem, even though I did the rest of it correctly, which was a bit unfair. The second midterm was very hand-wavey and obscure, but I actually did better on it because the problems looked more difficult than they actually were, and he gave us one less question than the first midterm. He also gave us some very simple problems that seemed to be free points. Also, on all exams he gives 5 free extra credit points for writing the integrity statement and signing it. Last, the final was definitely easier than both midterms by a decent amount, but there were a lot of spots where you could make silly mistakes, and I definitely did. Still, in the end he seemed to have realized his mistakes and curved the final grade, which I greatly appreciate.
Also, every week he sends out an optional weekly problem set which are quite difficult, but he basically gives all of the answers in office hours. The only inconvenience is that this is basically the only way to get answers and attending 2-3 office hours every week is a hassle. Getting these answers is key, though, as he uses the exact same questions on the graded homework assignments, and the exam questions are also similar.
Overall, if there's another choice, I'd probably take them over Barr, but in the end, he wasn't too too bad. He's a little bit "too nice" if that makes sense, like borderline fake since he used to work at Disney, but he's very intelligent, helpful, and caring. So, he's really hit or miss based on how strong your chemistry background is. The class seems way harder at the time, but in hindsight, Barr's class was probably average for a general Chemistry class. The workload is very light.

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.

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.