What Types of Professors Will I Have at a US University?

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By Matt Killorin
Last updated on August 9, 2023

Will your first US university class have an assistant professor, a guest lecturer, or an adjunct? Find out about the different types of instructors and classes you may encounter when you study in the US.

There are many types of professors at US universities. In this photo, a faculty lecturer stands in front of a whiteboard, next to a television broadcasting a guest speaker, in front of a class of international students.

As an international student starting your first semester at a university in the United States, you may be wondering why some classes are taught by professors and others by different types of instructors. What is an assistant professor, an adjunct professor, or a professor emeritus? What impact does each have on courses, grades, and your ability to learn a topic? Read on to learn more about the types of instructors and classes at US universities, as well as the proper etiquette for asking questions and interacting with professors. 

What is the Difference Between Professors, Lecturers, and Teaching Assistants? 

For instructors at US universities, tenure status is the main difference between the types of teaching roles. A tenured professor is an instructor with a permanent post at a university. If an instructor does not have tenure, it means they do not have a permanent contract. Does that mean you will receive a better education from a tenured professor than you would from a teaching assistant? Not necessarily. 

New instructors, graduate students, and doctoral candidates teach many lower-level courses at US universities. As your classes become more advanced, you will enter the classrooms of those more advanced or experienced teachers. With that in mind, you should feel confident that the course you are taking is taught by a proficient, knowledgeable instructor who has the strength of the department as a whole behind them — no matter their job title. Let’s take a closer look at each role. 

Assistant Professor

An assistant professorship is the first step in a career as a higher education instructor. Assistant professor positions in the United States are highly competitive, as they often lead to tenured positions at universities, so you can assume that your teacher is very good at what they do. 

What classes do assistant professors teach? Many assistant professors teach a wide array of classes, but you can assume that they will lead the lower or less advanced courses that you will encounter within the first couple years of your academic program.

Associate Professor

In the United States, assistant professors are promoted to associate professors — where they often receive tenure — before they become full professors. If you have an associate professor, it is likely that they have more publications, research, and/or teaching experience than your assistant professors.  

What classes do associate professors teach? Generally, associate professors teach more mid-level and advanced courses. 


Professor, or full professor, is the highest promotion an instructor can achieve at a university. Most full professors have doctorate degrees and have been tenured for years. They often also play important roles in establishing the university curriculum for their discipline. Some institutions and disciplines also have distinguished and endowed professors. Distinguished professors are leaders in their field of study. Endowed professors are similar to distinguished professors, but their role is often funded by private or public donors. 

What classes do professors teach? Professors generally teach higher-level undergraduate or graduate-level courses. 

Professor Emeritus

Professor Emeritus is an honorary title given to a retired professor to recognize distinguished academic service at a university. The title of professor emeritus may also be given to a person who is well known as an expert in a field, but may not be a classically trained professor. An author, for example, may be recognized by a university with the title of professor emeritus. 

What classes do professors emeriti teach? While professors emeriti sometimes stay on at a university to teach less rigorous courses part-time or a single course, generally they are retired and no longer teaching. 

Visiting Professor

Visiting professors are high-ranking instructors who are usually part of a different institution or university faculty. Visiting professors are generally experts in a field of study, offering students at your university their perspective on a specific area or course. Sometimes visiting professors are hired by a university to fill a faculty vacancy until it can make a permanent hire. 

What classes do visiting professors teach? Visiting professors are considered scholars in their field, so they are usually brought to a school to teach higher-level courses. Recent trends at higher education institutions in the US include hiring more visiting professors to attract students to lower-level classes or to fill a gap before hiring a new professor. 

Adjunct Professor

Adjunct professors are not on a tenure track at your university and may teach at several schools to make a living. Adjuncts are experts in a discipline. Many have doctoral degrees and extensive teaching experience, but are not officially part of the university’s full-time faculty. Some adjunct professors enjoy the flexibility of their role, while many others hope to obtain an assistant or associate position at an institution. 

What classes do adjunct professors teach? Adjunct professors generally teach entry-level undergraduate courses or lectures. 

Teaching Assistant (TA)

A teaching assistant is usually a graduate student taking master’s- or doctoral-level classes in the same discipline they teach. A teaching assistant may assist in a different professor’s class or lab or lecture, or lead a class themselves. Most TAs teach courses to help pay tuition or living expenses, and others must teach as part of their degree program. 

What classes do TAs teach? Teaching assistants and adjunct professors generally teach the same courses — survey or introductory classes at the undergraduate level.


Lecturers are staff members — often from outside academia — who teach students at both the undergraduate and graduate levels. Lecturers usually earn their roles based on professional merit and career experience and can offer real, current perspectives that many professors who work in education cannot. Lecturers are especially found in professional courses of study, such as business and finance. 

What classes do lecturers teach? Lecturers bring value to an institution because they are professional experts within a field, not academic experts — that means their experience comes from practice and not theory. As a result, they generally lecture or conduct seminars or classes as part of professional degree programs — from PharmD programs to law school. 

Guest Lecturer

Guest lecturers are much like lecturers except they are not part of the institution. Guest lecturers are often professional experts. They may have recently written a book, are in the media, or are alumni with a rich perspective on a relevant topic. Guest lecturers generally instruct a portion or segment of a course and do not stay on campus as teachers for long periods. Many times, guest lecturers are on a university circuit or speaking tour, stopping for a one-night appearance or special event.

What classes do guest lecturers teach? Expect guest lecturers to speak on a specific topic with a lot of professional input. Since their topics are often directed to a very specific audience, guest lectures are a great opportunity to network with other like-minded students and professionals. 

What Types of Classes Will I Take at US Universities? 

US universities embrace all learning types and instructors will apply a lecture-based or experiential learning methodology depending on what they are trying to teach and where they are in the lesson plan. For example, a lecture may be used to introduce a concept, and then small-group breakout sessions may be used to reinforce the concepts learned in the lecture hall. 

Different class types require different behavior from students to ensure they get the most out of their learning opportunities. For instance, it may be rude to discuss a concept with a classmate during the middle of a lecture by the professor, whereas not participating in a small group breakout discussion may earn you a low grade. Let’s take a look at where these different types of classes are hosted, who usually teaches, and what your behavioral expectations are in each. 

Large Lecture Halls 

Large lecture-style classes can have hundreds of students in one large room with the professor up front, perhaps in front of a whiteboard or a digital display. These classes can range in complexity, with most survey classes and introductory courses being taught in lecture halls by TAs, adjuncts, or assistant professors, and many complex classes with higher profile professors.

In lectures, a student may ask questions, or a professor may call on a student, but usually, students are meant to listen, take notes, and absorb information. 

Small Discussion Classes 

If students are meant to listen in lectures, they are meant to speak and participate in small discussion classes. Many small discussions are complementary classes to lectures — students learn the lecture concept and put their learning into practice in smaller groups. Discussion classes happen in rooms that most resemble classrooms, with either desks or large tables that invite participation. Many small discussion classrooms host elective courses that students must take as requirements for their major. Small discussions may be more likely to be run by associate or assistant professors, depending on the academic department and overall university policies. 

In small discussions, students work with each other discussing a topic, completing projects or reports, and give presentations. These types of classes are more experiential than lectures. 

Learn more about experiential learning >> 


Lab classes are usually science-based, but students may also take a writing lab to improve their writing skills. Whether you are conducting scientific experiments or perfecting your five-paragraph essay, a lab will usually be taught by an assistant, adjunct, or associate professor, and rarely by a full professor. Labs require hands-on, experiential learning. You may be working alone or in small groups with your classmates. Generally, you will work on an experiment or project together in a lab. 

Laboratories are similar to small discussion classes — questions, comments, and class participation are not only encouraged, but often required to complete your course. Also, many labs are companion classes to lectures at US universities. 

Online/Virtual Classes

At this point, every student should know what an online or virtual class is! Due to the coronavirus pandemic, all types of classes have gone remote, which means that the same rules apply to lectures and small discussion classes as they would to in-person classrooms. Lectures are intended to be listened to, with less participation, whereas labs and small classes require more interaction and discussion. 

Online classes can suffer when too many people participate at the same time, making it difficult to carry out a discussion. Be mindful — especially in smaller, discussion-based classes — of interruptions. Use the chat, “hand raise” function, and other tools to help keep order. 

Getting to Know Your Professors and Finding Success

Most universities believe professors and instructors of all types should be accessible to their students. Whether by email, phone, office hours, or small group appointments, you will always have access to your teachers if you have questions or concerns. At the beginning of each semester, instructors usually share their contact information and preferred methods of communication, as well as their office hours. 

If your professor is a full professor, it is OK to address them as “professor” either in person or by email. If your instructors have PhDs, you may also call them doctors (for example, “Dr. Smith”). If you are unsure, or if the instructor falls in a different category, you may ask them how they would like to be addressed or use the formal “Mr.,” “Ms.,” or “Mrs.” (They may also indicate their preference on the class syllabus.)

If you are looking to find out what other students think about an instructor, or if you want to leave a comment about an instructor you recently had, sites where you can “rate my professor” provide real feedback from real students. Use sites like these to determine how difficult a class may be or whether a student would take another class taught by the same instructor. There is also information about the class type and even tags telling future students if the location is accessible. 

Remember, your professors and teachers are here to help you succeed. You will quickly learn the differences between class types and professors, and many people — from advisors to classmates — are available to help you if you have any questions. While it can be scary at first, navigating your university campus and getting to know professors and different types of classes are exciting parts of the US college experience.

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