Thomas
I have been enrolled in 400-person economics lectures, 12-person spanish classes, and many things in between. Any class larger than about 20, larger than can easily facilitate a discussion that involves each student, will also include a weekly section led by either the teacher himself or, in my experience, highly-qualified TAs (often Ph.D. students or other graduate students). I have found that teachers are never satisfied to approach heavily discussed topics in the standard way, but seek new ways to make topics interesting or useful. I have found that my least satisfying class still has loads to offer, and it is more often an issue of my having found a subject that interests me more or less - teachers are, as I've found, unwaveringly qualified and insightful. I have never had any issue getting into a class, even as a freshman, or finding ways to speak one-on-one with my teachers. Even the teachers I've had in the largest classes make an effort to personally know as many students as possible, and have been extremely personable and excited to help in office hours. It is also a common occurrence for a teacher to extend a certain conversation outside traditional class hours, either meeting for coffee or inviting a student over to their house.
Gabrielle
In many instances, professors will know students names. In the rare likelihood that they do not, many professors will know a student's name upon introduction. With the open curriculum, students are often only in classes that they want to be in, so there is a lot of participation in every class. Some of my favorite classes taken have been in the public health department, also my concentration. The professors really get to know the students and there is so much conversation that students almost feel like they are teaching the course.
Solomon
Academics at Brown are challenging and fast-paced. Every class is relevant, and students must be responsible about attending class and doing assignments to succeed. There are serious discrepancies between the Humanities and Science course grading policies. The Humanities at Brown have much greater grade inflation, where the sciences do not curve, but generally are more competitive. Professors are easily contacted at Brown, as the school focuses largely on its undergraduates. Professors always give students opportunities to meet with them by appointment and during their office hours, and generally do a good job responding to their emails. Class participation in large lecture classes is less common, but there are a very large amount of small seminars for students offered in every department, and discussion is strongly encouraged in those courses. I am currently pursuing a degree in Biology, and the department has been very supportive of me.
Ana
Academics are stellar at Brown. Students in the sciences tend to have larger class sizes, especially at the intro level of classes (Chem, Econ, and Bio have huge intro classes), but they quickly get smaller until many senior-level classes are seminars, even in these concentrations.
Students often study in groups, and the libraries have rooms you can reserve with white boards and good lighting for studying with friends at any hour of the day.
Katherine
Although the professors vary in terms of teaching ability, I have not had one professor who wasn't, well, nice. So far, all have been very easy to reach out during office hours and were friendly. Some departments have notoriously bad professors (math) in the lower level classes. Thankfully, Brown offers free group and one-on-one tutoring services for popular classes like intro chem or intro math. My experience with professors have generally been quite positive. I credit this to shopping period and the Critical Review (which is like a ratemyprofessor for Brown) which has enabled me to pick classes with professors I like.
Jonathan
Introductory classes can be large, and professors vary in their willingness of see you in office hours. But most professors are excellent in answering your questions. If you don't get to know at least one professor well during your time at Brown, that's your own fault. The professors are receptive, and many undergrads do research with professors as we don't have as many graduate students as other schools. Class participation is heavy in seminars and smaller classes. If you have a dynamic professor in a large class, there can be participation. But usually the class participation is much lower in the large lecture classes. The New Curriculum means that you will have to design your own education, so advising would be essential. I would suggest you talk to upperclassmen in the first few weeks just to get an idea of the classes at Brown that students take/good professors. The faculty advisor won't necessarily know that, they're more for concentration advising and thinking about your future.
Rory
I took a lot of classes in the Psychology and Neuroscience departments. Both were top-notch.
Jimmy
This may be one of Brown's strongest offerings. Professors are world-renown--and accessible! Very few classes are run by teaching assistants. Many professors will get to know you personally. You can take nearly any class you want! Getting around pre-requisites is really not as hard as it sounds. There are so many "must-take" classes that you're only really limited by your own time. If what you're interested in isn't offered, start up your own class, or your own major for that matter. Students are not competitive, only hard working.
Harper
I'm a pre-med student at Brown, so I started off my freshman year taking lots of big lecture classes towards my pre-med reqs and for my major. While I enjoyed big lecture classes because I wasn't usually one to ask questions in class and therefore, didn't feel pressured to initiate any conversation, the downside is that the professors don't know your name, unless you go to him or her for outside help during office hours. I never really did that, until second semester for my Cell & Molecular Bio and Neurobio courses. However, classes do become smaller once you get into the higher level classes. Because Brown doesn't have any academic requirements (besides the ones towards your track / concentration), you're really free to explore. I really have a penchant for literature so second semester I took a Romantic Lit class and read King Arthur, Sir Gawain, and Chaucer, which I really did enjoy. You're free to audit classes as well, and last semseter I audited City Politics with Morone (so good-- totally recommended!) Students I found are generally not so much competitive amongst each other, but with themselves. Everyone is constantly striving to do their best, and seeing others aruond you being so motivated, you naturally want to be more motivated as well.
Taylor
Very challenging, but can be negotiated quite easily with a bit of thinking. It really is what you make it. Professors and advisers are accessible and students are not super competitive. Intellectualism is rampant...sometimes annoyingly so.