CS 21: Intro to Computer Science - Spring 2021

Welcome to CS21. This course will introduce fundamental ideas in computer science while also teaching you how to write computer programs. We will study algorithms for solving problems and implement solutions in the Python programming language. Python is an interpreted language that is known for its ease of use. We also introduce object-oriented programming and data structures. A deeper coverage of these topics will be presented in CS 35.

This course is appropriate for all students who want to learn how to write computer programs and think like computer scientists. It is the usual first course for computer science majors and minors. Students with advanced placement credit or extensive programming experience should place out of this course and instead begin with CS31 or CS35.

Meeting Times:

All times listed are local to Swarthmore (US/Eastern time).

We will primarily be using the online book How to think like a computer scientist: Learning with Python by Elkner, Downey and Meyers.

See the Schedule for each week’s reading assignment.

Here are a few other useful online resources:

By the end of the course, we hope that you will have developed the following skills:

Grades will be weighted as follows:

As noted above, a substantial portion of your grade will be based on your class participation in Zoom. Here are some tips for making our remote class time most effective:

This course features weekly lab assignments which are the largest component of your course grade. Lab attendance is required by all students. You must attend the lab session for which you are enrolled.

Lab assignments will typically be released on Sunday at the beginning of the week and will be due by midnight on Saturday. You are strongly encouraged to start early and to attend the ninja sessions for extra practice.

You will submit your assignments electronically using the handin21 program. You may submit your assignment multiple times, and a history of previous submissions will be saved. You are encouraged to submit your work regularly.

Academic honesty is required in all your work. Under no circumstances may you hand in work done with or by someone else under your own name. Discussing ideas and approaches to problems with others on a general level is encouraged, but you should never share your solutions with anyone else nor allow others to share solutions with you. You may not examine solutions belonging to someone else, nor may you let anyone else look at or make a copy of your solutions. This includes, but is not limited to, obtaining solutions from students who previously took the course or solutions that can be found online. You may not share information about your solution in such a manner that a student could reconstruct your solution in a meaningful way (such as by dictation, providing a detailed outline, or discussing specific aspects of the solution). You may not share your solutions even after the due date of the assignment.

In your solutions, you are permitted to include material which was distributed in class, material which is found in the course textbook, and material developed by or with an assigned partner. In these cases, you should always include detailed comments indicating on which parts of the assignment you received help and what your sources were.

When working on quizzes, exams, or similar assessments, you are not permitted to communicate with anyone about the exam during the entire examination period (even if you have already submitted your work). You are not permitted to use any resources to complete the exam other than those explicitly permitted by course policy. (For instance, you may not look at the course website during the exam unless explicitly permitted by the instructor when the exam is distributed.)

Failure to abide by these rules constitutes academic dishonesty and will lead to a hearing of the College Judiciary Committee. According to the Faculty Handbook:

This policy applies to all course work, including but not limited to code, written solutions (e.g. proofs, analyses, reports, etc.), exams, and so on. This is not meant to be an enumeration of all possible violations; students are responsible for seeking clarification if there is any doubt about the level of permissible communication.

The general ethos of this policy is that actions which shortcut the learning process are forbidden while actions which promote learning are encouraged. Studying lecture materials together, for example, provides an additional avenue for learning and is encouraged. Using a classmate’s solution, however, is prohibited because it avoids the learning process entirely. If you have any questions about what is or is not permissible, please contact your instructor.

Lauri Courtenay is the CS Department’s Academic Support Coordinator. She will be working closely with our student mentors, also known as Ninjas, to help you learn how to program and think like a computer scientist. The CS21 Ninjas will assist us in class and run evening study sessions The CS21 Ninjas (student mentors) are: Jack Ballou, Olivia Fey, Vlad Hes, Alice Huang, Sherry Huang, Martina Kampel, Christine Mason, Jacob Park, Xoe Porterfield, Anwyn Urquhart, Vika Zakharova.

Programming is not a dry mechanical process, but a form of art. Well written code has an aesthetic appeal while poor form can make other programmers and instructors cringe. Programming assignments will be graded based on style and correctness. Good programming practices usually include many of the following principles:

When using the following commands:

C-x means hold the control key while also pressing the x key, the same way you might use C-c to copy.

For commands with the escape key, just press escape and release it—​don’t hold it down.

Links that are related to the course may be posted here. If you have suggestions for links, let us know.