This syllabus is a living document; please be aware that many elements on this page will change throughout the semester, including the course schedule. It is the student's responsibility to review this page periodically for updates.

Class Info

Section 3: TR 9:55–11:10am, Science Center 256
Professor: Richard Wicentowski
email: richardw @
Office: Science Center 292
Phone: x5643
Office hours: 1:00-4:00 Thursday and by appointment

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 CS35.

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.

Required Textbook:

Introduction to Computation and Programming Using Python by John V. Guttag
ISBN: 978-0262525008
We are using the revised and expanded edition
(a copy will be on reserve at Cornell Library)

Goals for the course:

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


This is a tentative schedule; it may change as we go.
1Jan 21   Introduction to Python and Unix
§2.1 (skip § 2.1.3), §3.2
Lab 0: linux & xemacs
Jan 23  
2Jan 28   Strings, lists, and for loops
§2.3, §3.4
Lab 1: First programs
Jan 30  
3Feb 04   Booleans, If/else
Lab 2: Numbers and Strings
Feb 06 Quiz 1
Study Guide
4Feb 11   While loops
Lab 3: Conditions and Booleans
Feb 13  
5Feb 18   Functions, objects
§4.1, §4.2
Lab 4: while loops and random numbers
Feb 20 Quiz 2
Study Guide
6Feb 25   Graphics, using objects Lab 5: Baby Names
Feb 27  
7Mar 04   Top-Down Design, File I/O
§4.6, Chapter 6
Lab 6: Graphics and Objects
Mar 06 Quiz 3
Study Guide
Trace question 8

Mar 11

Spring Break

Mar 13

8Mar 18   More Top-Down Design
Lab 7: Simon
Mar 20  
9Mar 25   Searching, Analysis of Algorithms
§9.1, §9.3.1-§9.3.3, §10.1
Lab 8: Elections
Mar 27 Quiz 4
Study Guide
10Apr 01   Sorting, Analysis of Algorithms
Lab 9: Searching and visualization
Apr 03  
11Apr 08   Recursion
Lab 10: Text Filtering
Apr 10 Quiz 5
Study Guide
12Apr 15   Defining new classes
Chapter 8
Lab 11: Recursion
Apr 17  
13Apr 22   Linked lists
Lab 12: 2048
Apr 24 Quiz 6
Study Guide
14Apr 29   Advanced Topics, Wrap-up Lab 13: Linked Lists
May 01  

May 15

Study/review session (Thursday 7pm-9pm - SC 256)

May 16

Study/review session (Friday 7pm-9pm - SC 256)

May 17

Final exam (Saturday 9am-noon - SC 101)

Student Support

CS21 Ninjas are student mentors who will assist me in class and run evening study sessions in the birds' nest (Sci 256). The CS21 Ninjas (student mentors) are: Terry Martin, Laina Chin, Karl Sadueste, Izzi Baskin, Alex Simms, Winnie Ngo and Justin Cosentino. Terry and Laina will be helping out in our class. You will get to meet the other ninjas in the lab and in the study sessions.

Study sessions

You are invited -- and encouraged -- to participate in Ninja evening study sessions to prepare for quizzes, to discuss programming concepts, and to get friendly assistance in working on lab assignments. Our CS mentoring team is dedicated to helping students, who have no prior knowledge of computer science, learn to program in Python while keeping their senses of humor intact. As an added bonus, snacks will be provided at the sessions. The sessions are held:

Weekly Evening Ninja Sessions
Wednesdays 7—9pm Sci Center 256
Thursdays 7—10pm Sci Center 256

Lab Attendance Policy

This course features weekly lab assignments which are the largest component of your course grade. Lab attendance is required by all students, unless you have already completed and submitted the lab assignment for the week. Additionally, the CS labs are open 24 hours a day, 7 days a week for you to use for CS21 lab assignments. While you must attend the lab session for which you are registered, you may optionally attend additional lab sessions, provided space is available. In case of space constraints, students registered for the lab will have seating priority.

Weekly Lab Sessions
1:05—2:35pm Tuesdays Knerr Science Center 256
2:45—4:15pm Tuesdays Knerr Science Center 256
1:05—2:35pm Thursdays Ylvisaker Science Center 256
2:45—4:15pm Thursdays Waterman Science Center 256

Accessing the CS labs after hours

You can use your ID to gain access to the computer labs at nights and on the weekends. Just wave your ID over the microprox reader next to the lab doors. When the green light goes on, just push on the door handle to get in (the door knob will not turn). If the green light doesn't go on, then we need to enter your microprox number into the system. email if you have problems with this. If the building is locked, you can use your ID to enter the door between Martin and Cornell library. For this class, your ID will give you access to the labs in rooms 238, 240 and 256.

How to Succeed in CS 21

Academic Accommodations

If you believe that you need accommodations for a disability, please contact Leslie Hempling in the Office of Student Disability Services, located in Parrish 130, or e-mail lhempli1 to set up an appointment to discuss your needs and the process for requesting accommodations. Leslie Hempling is responsible for reviewing and approving disability-related accommodation requests and, as appropriate, she will issue students with documented disabilities an Accommodation Authorization Letter. Since accommodations may require early planning and are not retroactive, please contact her as soon as possible. For details about the Student Disabilities Service and the accomodations process, visit the Office of Student Disability Services.

You are also welcome to contact me privately to discuss your academic needs. However, all disability-related accommodations must be arranged through Leslie Hempling in the Office Of Student Disability Services.

To receive an accommodation for a course activity, you must have an Accomodation Authorization letter from Leslie Hempling and you need to meet with me to work out the details of your accommodation at least one week prior to the activity.


Grades will be weighted as follows:
25%Final Exam
5%Class Participation

Quiz policy

Quizzes will be given at the beginning of class on the days posted in the Schedule. Please look over these dates carefully and contact the professor in advance if you cannot be in class for a quiz.

If you are not present at the start of class on the day of a quiz, but make it to class before the end, then you may take the quiz. Otherwise you will receive a zero for that quiz.

Lab assignment policy

Lab assignments will be posted on the Schedule on Sunday and will be due before midnight the following Saturday night. You are strongly encouraged to start early and to attend the study sessions for extra practice.

You will submit you assignments electronically using the handin21 program. You may submit your assignment multiple times, but each submission overwrites the previous one and only the final submission will be graded.

Late assignments will normally not be accepted. If you have a legitimate reason for needing extra time, such as an illness or needing to leave campus, you must contact the professor at least a day before the deadline to have your request for an extension considered.

Even if you do not fully complete an assignment, you should always submit what you have done to receive partial credit.

Programming Style

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:

Also, look over the Python Code Style Guide for more details and some examples of good code style.

Academic Integrity

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. Your code should never be shared with anyone; you may not examine or use code belonging to someone else, nor may you let anyone else look at or make a copy of your code. This includes, but is not limited to, obtaining solutions from students who previously took the course or code that can be found online. You may not share solutions after the due date of the assignment.

Discussing ideas and approaches to problems with others on a general level is fine (in fact, we encourage you to discuss general strategies with each other), but you should never read anyone else's code or let anyone else read your code. All code you submit must be your own with the following permissible exceptions: code distributed in class and code found in the course text book. In these cases, you should always include detailed comments that indicates on which parts of the assignment you received help, and what your sources were.

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: "Because plagiarism is considered to be so serious a transgression, it is the opinion of the faculty that for the first offense, failure in the course and, as appropriate, suspension for a semester or deprivation of the degree in that year is suitable; for a second offense, the penalty should normally be expulsion."

Please contact me if you have any questions about what is permissible in this course.

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

  • Python Code Style Guide
  • Using Unix
  • Basic Unix Commands
  • Python Documentation (Note: we are using v2.7)
  • How To Think Like a Computer Scientist: Python for Software Design (Free online book)
  • Emacs reference card