Course Information


The CS 61 series is an introduction to computer science, with particular emphasis on software and on machines from a programmer's point of view.

  1. CS 61A concentrates on the idea of abstraction, allowing the programmer to think in terms appropriate to the problem rather than in low-level operations dictated by the computer hardware.
  2. CS 61B deals with the more advanced engineering aspects of software, such as constructing and analyzing large programs.
  3. CS 61C focuses on machines and how they execute programs.

In CS 61A, we are interested in teaching you about programming, not about how to use one particular programming language. We consider a series of techniques for controlling program complexity, such as functional programming, data abstraction, and object-oriented programming.

CS 61A primarily uses the Python 3 programming language. Python is a popular language in both industry and academia. It is also particularly well-suited to the task of exploring the topics taught in this course. It is an open-source language developed by a large volunteer community that prides itself on the diversity of its contributors. We will also use two other languages in the latter half of the course: the Scheme programming language and the Structured Query Language (SQL).

Mastery of a particular programming language is a very useful side effect of CS 61A. However, our goal is not to dictate what language you use in your future endeavors. Instead, our hope is that once you have learned the concepts involved in programming, you will find that picking up a new programming language is but a few days' work.


Math 1A is a corequisite for CS 61A. (That is, it may be taken concurrently.) Math 10A or Math 16A are also fine.

There are no formal programming-related prerequisites for admission to CS 61A, but it's not the right first course for all students. Many CS 61A students have had significant prior programming experience, including prior coursework. Some students take the course without any prior programming experience, but they typically must work substantially harder to master the material, perhaps simply because they have less practice working with programs. If you have limited prior experience and you find it challenging to complete all of the required coursework in the first three weeks, you should seriously consider taking another course first. You'll likely have a better experience taking 61A later, and you won't fall behind in any meaningful way by taking one of the alternatives below prior to taking 61A.


If you want to build programming experience before taking CS 61A, we recommend that you take one of these courses first. You can always take CS 61A in a future semester (including the summer).

CS 10

CS 10: The Beauty and Joy of Computing provides a bird's-eye view of the field of computer science. The course teaches students how to program using Snap (based on Scratch), one of the friendliest programming languages ever invented, as well as Python, the same language used in 61A. But the course is far more than just learning to program! You'll also learn about some big ideas of computing, such as abstraction, design, recursion, concurrency, simulations, and the limits of computation. You'll also see some beautiful applications of computing that have changed the world, as well as talk about the history of computing and where it will go in the future.

Data 8

Data 8: The Foundations of Data Science is an introduction to data science designed to be accessible and useful for all Berkeley students, and built for students without prior programming experience. The course teaches students to program in Python 3, but covers a much smaller subset of the language than CS 61A. Most of the course focuses on data processing and statistical techniques that are central to using computers to answer questions about the world. The overlap between Data 8 and CS 61A is small (perhaps 25%), but the programming skill you will acquire in Data 8 will help you maintain the faster pace of CS 61A.

Course Format

The course includes many events and opportunities for learning: lecture, lab, discussion, office hours, group mentoring, and one-on-one tutoring. Weekly lab and discussion sections are typically the most valuable events to attend. For the rest, your attendance is optional. These events exist to help you learn, and so you are advised to attend as many as required to master the material.


There are three 50-minute lectures per week. Videos and slides will be posted the night before each lecture. Most students prefer the videos to live lecture, but you should try both and decide for yourself. If you choose to watch the videos, watch them the day of live lecture. Please do not fall behind; many students who fall behind have a rough time trying to catch up.


There are both lab and discussion sections each week. These sections are run by an amazing group of teaching assistants who have been carefully selected for their ability, enthusiasm, and dedication to learning. Getting to know your TA is an excellent way to succeed in this course. Participation in lab and discussion determines your participation score for the course.

Please attend the section that you have chosen on Sign-up Genius. If you want to switch sections, please also switch your enrollment there so that we can keep track of who is attending which section. It's best to attend one section regularly, rather than attempting to move around week to week.

Office Hours

Attending office hours is another excellent way to succeed in this course. You can ask questions about the material, receive guidance on assignments, work with peers and course staff in a small group setting, find project partners, and learn about computer science at Berkeley.


Each week, there will be problems assigned for you to work on, most of which will involve writing, debugging, and discussing programs. These assignments come in three categories: lab exercises, homework assignments, and projects.


Lab exercises are designed to introduce a new topic. You can complete and submit these during the scheduled lab sections, or on your own time before the scheduled due date. Most students find that attending lab is much more useful than working on lab assignments independently.

Lab exercises are scored on correct completion. To receive credit, you must complete all of the problems that are not marked as optional.

Check-offs are conversations about lab material that take place in lab. A course staff member will check your understanding of lab assignments by asking you a few short questions about the current lab or the previous lab. If you answer their questions in a way that demonstrates good progress, they will give you check-off credit. Check-offs are a great opportunity to receive one-on-one feedback and gain a deeper understanding of the material.


Homework assignments are meant to illustrate and explore new topics. You are encouraged to discuss the homework with other students, as long as you write your own code and submit your own work. Finding a study group is a great idea. The purpose of homework is for you to learn the course material, not to prove that you already know it. Therefore, you can expect to receive substantial assistance from the course staff. Note that there is no partial credit for homework assignments; you either receive credit or not. Credit is given for submissions that correctly solve the problems or demonstrate considerable progress and obvious sustained effort toward a solution.

You are responsible for writing solutions yourself. If you are stuck on a problem, come get help instead of copying the answer from someone else or the Internet; you'll still get credit and won't be flagged for cheating.


Projects are larger assignments intended to combine ideas from the course in interesting ways. Some projects can be completed in pairs. When working in pairs, you should work together to ensure that both of you understand the complete results. We recommend finding a project partner in your section. Your TA will help. You may also work alone on all projects, although partners are recommended for the paired projects. Projects are graded on both correctness and composition.


The first midterm exam will be held 8-10 PM Monday, September 10. You are permitted to bring one double-sided, letter-sized, handwritten sheets of notes.

The second midterm exam will be held 8-10 PM Wednesday, October 17. You are permitted to bring two double-sided, letter-sized, handwritten sheets of notes. You can save your notes from Midterm 1 and bring them to Midterm 2.

The final exam will be held 7-10 PM Wednesday, December 12. You are permitted to bring three double-sided, letter-sized, handwritten sheets of notes.

There are no alternate midterm times. For students with a valid excuse for missing a midterm, notify us before the exam in question, and we will estimate a score for that exam by weighting your other two exams.

If you have two final exams at the same time, you may be approved to take the 61A final the following morning, 8-11 AM Thursday, December 13. Aside from a direct conflict with another exam, there are no alternate final times allowed.



The online textbook for the course is Composing Programs, which was created specifically for this course. Readings for each lecture appear in the course schedule. We recommend that you complete the readings before attending lecture.

Computing Resources

If you are enrolled in the class, you may request a CS 61A instructional account. This account will allow you to use any EECS instructional lab computer in Soda or Cory Hall. You may use any lab you wish, as long as there is no class using the space.

Be respectful of the lab space. Please don't steal the chairs, and definitely do not eat or drink in the lab. Don't unplug anything; unplugged computers make our hard-working instructional computing team very sad. If you see someone disrupting the space, ask them to stop.

Labs are normally available for use at all times, but you need a card key for evening access. If you are a Berkeley student, your student ID will automatically grant you access to the Soda second floor labs. Otherwise, you can fill out an application from 387 Soda (the front desk).


Your course grade is computed using a point system with a total of 300 points.

  • Midterm 1, worth 40 points.
  • Midterm 2, worth 50 points.
  • The final exam, worth 75 points.
  • Four projects, worth 100 points.
  • Homework, worth 25 points.
  • Section participation, worth 10 points.

There are a handful extra credit points available throughout the semester, perhaps around 10, that are available to everyone.

Each letter grade for the course corresponds to a range of scores:

A+  ≥ 300    A  ≥ 285    A-  ≥ 270
B+  ≥ 250    B  ≥ 225    B-  ≥ 205
C+  ≥ 195    C  ≥ 185    C-  ≥ 175
D+  ≥ 170    D  ≥ 165    D-  ≥ 160

Your final score will be rounded to the nearest integer before being converted to a letter grade. 0.5 rounds up to 1, but 0.49 rounds down to 0.

There is no curve; your grade will depend only on how well you do, and not on how well everyone else does. Score thresholds are based on how students performed in previous semesters. It is possible that the instructors will adjust the thresholds in your favor, for example if exam scores are abnormally low, but that scenario is unlikely. More likely, these are the exact thresholds that will be used at the end of the course to assign grades (contrary to popular rumor).

Incomplete grades will be granted only for dire medical or personal emergencies that cause you to miss the final, and only if your work up to that point has been satisfactory. You must complete all coursework before the drop deadline to be considered for an incomplete grade.

Lab and Discussion Participation

Lab exercises, lab checkoffs, and discussion attendance are collectively worth 10 points.

You earn a participation credit for each of the following:

  • Submitting a lab assignment that passes all required tests (about 12 of these are available)
  • Completing a checkoff in lab (about 10 of these are available)
  • Attending discussion (about 12 of these are available)

Discussion 0 does not count for participation credit.

Your first 10 participation credits count as points: your section participation score. Any additional participation credits count only for exam recovery. Therefore, it's possible to earn a perfect score in the course by only participating in section for the first third of the semester.

Midterm Recovery Policy

After the required 10 points, the next 20 participation credits can help you earn midterm recovery points.

Note that there are more than 30 possible credits, so you can still miss a few participation credits and receive the maximum amount of midterm recovery.

We calculate your midterm recovery using the following logic, where participation is the number of participation credits you earn.

def midterm_recovery(your_exam_score, participation, max_exam_score, recovery_cap=20):
    if participation <= 10:
        return 0
        half_score = max_exam_score / 2
        max_recovery = max(0, (half_score - your_exam_score) / 2)
        recovery_count = participation - 10
        recovery_ratio = min(recovery_count, recovery_cap) / recovery_cap
        return max_recovery * recovery_ratio

According to this formula, if you receive more than half the available points on a midterm, then you don't recover any points. If you score just below half the points, you will recover a few points. If you score far below half the points, you will recover many points. The more participation credits you earn, the more midterm points will be recovered.

The purpose of this policy is to ensure that students who continue to invest time in the course througout the semester are able to pass.

It is not possible to recover points on the final exam.

Late Policy

If you cannot turn in an assignment on time, contact your TA and partner as early as possible. Depending on the circumstance, we may grant extensions.

  • Labs: We very rarely accept late lab submissions. There is no partial credit.
  • Homework: We very rarely accept late homework submissions. There is no partial credit.
  • Projects: Submissions within 24 hours after the deadline will receive 75% of the earned score. Submissions that are 24 hours or more after the deadline will receive 0 points. Each question is worth some points, so it is possible to earn partial credit on a project.

Learning Cooperatively

With the obvious exception of exams, we encourage you to discuss course activities with your friends and classmates as you are working on them. You will definitely learn more in this class if you work with others than if you do not. Ask questions, answer questions, and share ideas liberally.

Learning cooperatively is different from sharing answers. You shouldn't be showing your code to other students, except to your project partner or to someone who has already submitted the assignment and is helping you finish. If you are helping another student, don't just tell them the answer; they will learn very little and run into trouble on exams. Instead, try to guide them toward discovering the solution on their own. Problem solving practice is the key to progress in computer science.

Since you're working collaboratively, keep your project partner and TA informed. If some medical or personal emergency takes you away from the course for an extended period, or if you decide to drop the course for any reason, please don't just disappear silently! You should inform your project partner, so that nobody is depending on you to do something you can't finish.

Online Forum

If you have any questions, please post them to Piazza, the course discussion forum. Piazza allows you to learn from questions your fellow students have asked. We encourage you to answer each others' questions!

Piazza is the best and most reliable way to contact the course staff. You are also welcome to email, the instructor, or your TA directly.

Academic Honesty

Cooperation has a limit, and in CS 61A that limit is sharing code. You are free to discuss the problems with others beforehand, but you must write your own solutions. The only student with whom you can share code is your project partner.

Since this may be your first computer science class, exactly what constitutes as cheating might be unclear. If you are unsure if what you are doing is cheating, please clarify with the instructors or TAs. The following is a list of things you should NOT do. This list is not exhaustive, but covers most of the big offenses:

  • Do not copy code from any student who is not your partner.
  • Do not allow any student other than your partner to copy code from you.
  • Do not copy solutions from online sources such as Stack Overflow, Pastebin, and public repositories on GitHub.
  • Do not post your solutions publicly during or after the semester.

If you find a solution online, please submit a link to that solution anonymously. When we find an online solution, we ask the author to remove it. We also record the solution and use it to check for copying. By reporting online solutions, you help keep the course fair for everyone.

In summary, we expect you to hand in your own work, take your own tests, and complete your own projects. The assignments and evaluations are structured to help you learn, which is why you are here. The course staff works hard to put together this course, and we ask in return that you respect the integrity of the course by not misrepresenting your work.

Rather than copying someone else's work, ask for help. You are not alone in this course! The entire staff is here to help you succeed. If you invest the time to learn the material and complete the projects, you won't need to copy any answers.

A Parting Thought

Grades and penalties aren't the purpose of this course. We really just want you to learn. The entire staff is very excited to be teaching CS 61A this semester and we're looking forward to meeting such a large and enthusiastic group of students. We want all of you to be successful here. Welcome to CS 61A!