I took Calc AB in high school and passed the AP test with a 4, but had a hard time in this class. He's VERY organized, which is amazing compared to other math professors, but he can be socially awkward. He's really good-hearted though; if you visibly put in the effort, it'll pay off. He's pretty strict though, but it's a good thing because it rewards the students who pay attention.
His exams were hard while I took them, but looking at the answer keys (which he gave to us RIGHT AFTER the exam!) I always ended up going "duh, why didn't I do that??"

If I could do anything differently, I would focus more on completely understanding the material, rather than just doing the problems from the book to study.

Aschenbrenner is a fair grader on the curve. I got above the median on both midterms and the final and got a B+ in the class (even though my scores were 86, 75, 53, respectively). The midterms were what you'd expect, but the final was crazy-hard. The kind of final that students walk out of after 40 minutes becasue they can't answer any of the questions. The median on our final was a 44, so the curve figured in heavily.
Another thing I liked about him were that the HW problems were a good mix of easy and hard, so the harder questions on the exams didn't come as a big shock.

What I didn't like about him:
-His explanations in lecture are so-so, but the worst aspect was that when a student asked a question, he'd just repeat what he'd just said in lecture instead of actually explaining what he'd just said in lecture.
-He will not take questions via e-mail.
-He doesn't go into much explanation in office hours.

So, you'll be OK in this class because, fortunately, the textbook is very thorough in it's explanations and you can pepper your TA with questions instead of the professor. What Aschenbrenner does do, which is what you need the most, is give a good curve in the grading of this class.

Just know your stuff, lean on the book and your TA and you'll be OK.

Aschenbrenner was a horrible professor overall, but the material was easy because I didn't go to class (i.e. he teaches verbatim from the book, word for word).

If you want to pass the class, you can go to lecture, but if you want to get an A like I did, then rely solely on your TA and online lectures (I pretty much watched all of PatrickJMT's videos on Youtube, the examples he gives are very similar to the exams) If you can get Joe Hughes as your TA and ask him any questions you have, you will get an A in this class.

I think for me, the exams reflected the way I took the class. By only going to class I did not-so-great on the first midterm (67%, mean 66%, rank 66/204), but I did what I did above and did VERY well (91%, mean 58%, rank 9/192), and well enough on the final to get an A- (90%, mean 78%, rank 50/174),.

Having never taken a calculus class before, I was totally and absolutely bewildered in this class. Lectures are incredibly boring, he spelled things wrong, and once even got so lost in the only example that he ever presented to us that he GAVE UP solving it on the board. Beyond that, he never gave any examples during class, only focused on theory that we never needed to prove. TAs were no better; also taught meaningless theories without ever clearly explaining the problems we were actually expected to do. Midterm averages were always about 50%, and a concerning amount of students failed this class.

took him for 31A. Absolute bs, have taken calculus before and without prior knowledge I would've known absolutely nothing. Avoid him if you can, he is a good guy but a terrible lecturer.

Selling Single Variable Calculus by Rogawski for Math 31A/31B. Message if interested.
Also selling Multivariable Calculus by Rogawski for Math 32A/32B

That I'm taking two math classes this quarter helped me have a better view of him in retrospect. He is alright. His accent isn't at all bad unline what others say. He makes jokes that he thinks is funny. That's OK too. Go easy on the German guy.

Now, the lectures are as conceptual as they can get apart from some examples, so in order to have a good grasp of what's going on, you're recommended to read the lecture topics from the book in advance. Because in every lecture, you get to learn something that's not in the book that you can build on top of that, which gives you an edge and that epiphany you get when you (think that you) truly understand math. He's not always clear in what he says, not because of the accent, but sometimes he zones out and starts teaching to himself instead of the class. I had to ask questions where I didn't understand. So a bit low on clarity for that reason.

The exams are of understandable difficulty. Every midterm and the final will have that one question that'll screw you up, beside the majority plug-the-formula-and-get-the-answer questions. But turns out it was always my TA who came up with that one mothersucker question every midterm, so no blame on Aschenbrenner himself.

He invites you to ponder over the concepts that gives rise to other concepts, and provided you attend every lecture, you can see the flow.

Considering that you're going to take subsequent math classes such as 31B and 32A, be 31A a class that'll not give you an easy A but one that'll help you understand calculus. Because I'm taking both at the same time and they assume that you know how to derive and integrate like a piece of cake, and 31A is 80% derivatives in case you don't know.

If another professor is offered for this class, choose that professor only if you're lazy and that professor is clearer, or if you don't like professors with accents in general. Ensure the other professor is somewhat conceptual because calculator-like learning of calculus won't get you anywhere. So depending on your study habits and interest in the subject, choosing Aschenbrenner could be a gamble for you.

Having never taken a calculus class before, I was totally and absolutely bewildered in this class. Lectures are incredibly boring, he spelled things wrong, and once even got so lost in the only example that he ever presented to us that he GAVE UP solving it on the board. Beyond that, he never gave any examples during class, only focused on theory that we never needed to prove. TAs were no better; also taught meaningless theories without ever clearly explaining the problems we were actually expected to do. Midterm averages were always about 50%, and a concerning amount of students failed this class.

Aschenbrenner is a very nice guy, always easygoing. However, I would not recommend his class if you are not good at calculus. If you've taken it already in high school and done well, you should be fine, but this class is not for people who are just beginning calculus. Aschenbrenner goes right along with the book, which is convenient, and his homework is reasonable, but the midterms and the final will screw you over if you don't know how to expand on what is taught. They are nothing like the material in lectures or the homework, but instead are more abstract and ask students to go beyond his lessons (too beyond). I will say that there is a generous curve which helps those who are struggling, but you must do decently on the final (which is extremely difficult) in order to pass.

Be prepared for a super nice guy, but not the greatest teacher. He has a heavy accent which makes some things pretty hard to understand. His lectures move pretty fast and are sometimes hard to keep up with, so make sure if you take this class you are able to attend office hours. I took calculus in high school and this class is still difficult. He is friendly and is happy to answer questions in class, but his teaching is not the best. The homework is manageable and due every friday, followed by a quiz every tuesday. The first midterm was definitely more difficult than the homework problems and seemed slightly unfair. Most students were unable to complete the exam. If you took calculus in high school, I would say you're safe to take this class, but if this is your first time with the material this professor is not the one for you.