professor
David Hansen

Apr 2018

The kindest man. He explains number theory concepts so clearly. He makes even the most challenging of proofs feel simple. Workload is super easy and maneagable. There are about 6-7 problem sets per semester, which are fairly challenging, but I believe he grades homework based on effort. The Midterm is super straightforward. He also uploads a practice midterm that’s fairly similar to the actual one. A lot of people got 100s. Coming to class is pretty important, because there’s no textbook, and it’s hard to learn the material on your own. He is bad at updating courseworks, but he’ll always say in class what’s due when or what even the exams are. He is a fantastic lecturer, and even though you probably need to go to class to get a good grade, you’ll enjoy doing so.

Jun 2017

Hansen is... interesting. Little bit disorganized. Little bit crazy. Whole lotta fun. Definitely worth taking this class if you: A) Know how to write proofs really well (and I mean really well) B) Have covered the applications of the material before and want a strong theoretical foundation C) Love math (like, really really love it) If you fall into category C without being in either A/B, no worries! So long as you're talented, willing to put the work in (and/or give 0 shits about your GPA)then take the class! Hansen has an excellent teaching personality, maintaining his student's interest in lecture topics most would find dry. Watch out for quips - they come out of the blue but are absolutely hilarious. He's helpful in office hours, although he does expect you to not be useless as a math student and have done relevant background research in whatever it is you're asking about. Basically gives everyone a pass on the homework (as long as your avg grade is decent) but balances that by not curving the midterm or final - so study! I personally came into the class with very little relevant background - it ended up kicking my ass (and my GPA went up in flames), but also helped enormously in developing my study habits and my understanding of mathematics.

Mar 2017

Professor Hansen taught me to see math very differently. He has a lot of energy to teach the class. He's young, that is probably why. A lot of my classmates came to class because his energy drew them back (or because they fawned over him). I personally think I am prepared to take modern analysis if I do go that route and I think it should be easy since I scanned through the Rudin book and I feel I've learned most of it through this class. He has a lot of office hours and can really help guide you if you're stuck. From what I've heard from other students you can stop by his office and ask questions if he's there outside of his office hours. If you want to learn calculus in a different way and need to take analysis later, this class will prepare you, and Professor Hansen is great to take it from. If you have to get your Calculus requirements out of the way and don't really care how you do it, then this class may be a big challenge for you.

Aug 2015

Definitely one of the best classes I've taken here at Columbia. Hansen's an excellent lecturer, extremely clear, and best of all he can actually speak English which already makes him more competent than half of the math department. He's super chill, always ready and able to answer any questions that you might have. The class isn't a walk in the park but is easy by math major coursework standards. Only con to taking this class is there isn't much cryptography covered, but I guess there's Making, Breaking Codes if you're more interested in that.

Apr 2015

I am not a math person and I dislike calculus, and the only reason I kept showing up to lecture was because Dave is hilarious. He's young and nerdy and ridiculous. I would just laugh at him all class. He makes the best jokes which are usually very out of the blue and bizarre. He also is quite a good teacher, definitely one of the best math teachers I've ever encountered. Although I got a C- in this class, it wasn't anything he did wrong (I just hate math). He was available and helpful and friendly during office hours, and always answered questions during class. I think he's a great professor for a hard subject. Always in a good mood. Google him and you'll find his page about himself and it's absurd. He's such a goof in the best way possible. Clearly a very smart guy.

Jan 2015

I took Calculus I with Dave and it was amazing. I was extremely surprised when I went on Culpa and did not see any reviews written about him online. He brings a friendly atmosphere to the class and is 100% approachable in class as well as during his office hours. Dave really knows the material and occasionally adds interesting math problems and topics that diverge from the syllabus required concepts, but helps you think of math in a completely different way. They also show he has a genuine interest in what he teaches. Some of the teachers I have seen so far struggle to engage with the class or have a strangely tense atmosphere warding off all potential Calculus I students or students who just have an interest in math (not that only students who love math should take this class anyone and everyone should). He would often make random jokes here and there that always made the class laugh. The class goes over what you would expect Calculus I to be about: limits, differentials, integrals, the works. As long as you attend class, do the homework, and study you'll do great. We also did not need to use Webassign, which was amazing for any of you guys that do not like the idea of submitting complex answers online and having to buy the expensive code for the website. He allowed the class to use a one page sheet of paper with any notes or formulas for the final exam. WHO DOES THAT?? IT WAS DOUBLE-SIDED TOO!!! I highly recommend this class for anyone who needs to take Calculus I or just wants to take a class taught by him in general. Definitely a gold nugget or at least a silver nugget.

Jan 2015

Take Hansen's Calculus I course - you won't be disappointed. He's friendly, concise, precise, smart, good-looking, and all that but above all he's a truly good lecturer. Most of the time, he's done with lecture a little early even after always encouraging questions from students in the class. He speaks and writes fast, but never to the point where you can't follow, and you will almost always leave the class actually UNDERSTANDING the material - which I quickly discovered is rarely the case with most other professors in this Ivy institution. He always comes into the class with full command of the material and gives you just enough - never too much or too little. Dave's method is intuitive - a good mix of visuals and proofs. I sat in a few other sections prior to settling on this one, but it was only in Dave's where I felt like I was following the whole class. But the real success of his methods is probably the wealth of examples he goes through in class. They usually progress from simple to quite complicated, but this really helps you understand the materials because he's putting you in his shoes. Homework is quite straightforward and he's always willing to help during office hours or after class. Right before the midterm, he will post sample midterms and generally you'll glean a couple clues about how to go about the midterms from the sample. All in all, I was really pleased - I never took Calc before but he was such a good instructor and I got an A. He makes you want to do well and doesn't turn your life into a nightmare. Take his class already!

Jan 2015

I really enjoyed having him as a professor. If I could, I would take him for Calc II and so on. He really makes you sure the class understands what he is explaining and the class never felt overwhelming at any point. He's kooky-goofbally in a good way. He was also always open to questions right after class. I RECOMMEND HIM

Jan 2015

Hansen is the Calc Teacher you want to have. Recent PhD. student graduated from Brown among other top universities. Perfect English speaker, gives very good notes, and easy homeworks. He also rounds out your homework grade to a full 20 percent even if that is not your actual score on the homeworks. He is funny quirky, and a Steve Jobs wanna-be in terms of his style. On numerous occasions he also has said "I know none of you are Math majors so there is just no reason for me to complicate your lives by teaching you this." Understanding and considerate, and very patient with non-english speakers. The question is not how good Hansen is... it's if there are Math teachers worth taking other than him? My workload was 10 times easier than some of my peers in other sections. Note: Easy A if you took any Calculus in High School. Good GPA cushion.