CS21.1 -- Introduction to Comp Sci
Spring 2011

Schedule | Lab Sessions | Study Sessions | Succeeding | Grading | Quiz Policy | Lab Policy


  • The Final Exam Study Guide is now available.
  • There's a final exam ninja review session Thursday, May 5th from 7-9 p.m. in SCI 240.
  • The final exam is Saturday, May 7th at 2 p.m. in SCI 101.

Class Information

Room: Science Center 240
Class: MWF 10:30–11:20am
Professor: Charlie Garrod
Office: Science Center 255
Phone: 6071
Office hours: Wednesdays 1:30 - 3 p.m., or you can stop by whenever my door is open.

Welcome to CS21. This course will introduce fundamental ideas in computer science and teach 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 CS 33 or CS 35.

Required Textbook

Goals for the course

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

Student Support

Student Support Coordinator: Betsy Horner (Office: Science Center 257, Phone: 6062)

CS21 Ninjas (student mentors): Amanda Morrison, Ashley Oudenne, Brandon Snuggs, Emily Dolson, Haley Most, and Josh Bloom

Study sessions

The CS Ninjas will assist me in class and run study sessions in the main CS lab (Science Center 240) on the following evenings:

Day Time Location
Sunday 7-10pm Sci Center 240
Wednesday 7-9pm Sci Center 240

You are encouraged to participate in these study sessions to prepare for quizzes, to discuss programming concepts, and to get friendly assistance in working on homework 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, free food will be provided at the sessions.

Lab Sessions

The CS lab is open 24 hours a day, 7 days a week for you to use for CS21 lab assignments. In addition, the CS21 professors will be in the CS labs at the times listed below to help CS21 students with lab assignments. You are not required to attend the lab sessions, but you should take advantage of them to get assistance with your lab assignments. Any CS21 student is welcome to attend any session, and you may attend multiple sessions if you'd like.

Day Time Professor Location
Mondays 1:30-3:00 Knerr Science Center 240
Mondays 2:30-4:00 Garrod Science Center 240

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 local-staff@cs.swarthmore.edu 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 and 240.

How to Succeed in CS 21

Academic Accommodations

Academic accommodations are available for students with disabilities who are registered with Student Disability Services in the Dean's office. Students in need of disability accommodations should schedule an appointment with me early in the semester to discuss accommodations for this course that have been approved by the Dean's office. All requests must come through an accommodation letter from the Dean's office. To receive an accommodation for a course activity, your meeting with me must be at least one week prior to the activity.

Contact Tracey Rush at the Dean's office and follow these steps for obtaining accommodations.


Grades will be weighted as follows:
40%Lab assignments
5%Class Participation
25%Final Exam

Quiz policy

Quizzes will be given at the beginning of class on the days posted in the Announcements section of 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 policy

Lab assignments will typically be assigned on the Schedule in the middle of the week and will be due before midnight the following Tuesday 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 only be accepted if you contact the professor at least a day before the deadline with a legitimate reason for needing extra time, such as an illness or needing to leave campus.

Even if you do not fully complete an assignment, you should 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:

Academic Integrity

Academic honesty is required in all work you submit to be graded. With the exception of your lab partner on lab assignments, you may not submit work done with (or by) someone else, or examine or use work done by others to complete your own work. 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 sharing solutions after the due date of the assignment.

All code you submit must be your own with the following permissible exceptions: code distributed in class, code found in the course text book, and code worked on with an assigned partner. 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.

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. You may discuss assignment specifications and requirements with others in the class to be sure you understand the problem. In addition, you are allowed to work with others to help learn the course material. However, with the exception of your lab partner, you may not work with others on your assignments in any capacity.

``It is the opinion of the faculty that for an intentional first offense, failure in the course is normally appropriate. Suspension for a semester or deprivation of the degree in that year may also be appropriate when warranted by the seriousness of the offense.'' - Swarthmore College Bulletin (2008-2009, Section 7.1.2)

Please see me if there are any questions about what is permissible.


1 Jan 17   Introduction to Python and Unix
Zelle Chapters 1-2
Lab0: Unix & gvim
Lab1: First Programs
Jan 19  
Jan 21  
2 Jan 24 Quiz 1 Study Guide Numbers and Strings
Zelle Chapter 3 and Sections 4.1, 4.2, 4.3
Lab2: loops and strings
Jan 26  
Jan 28 Drop/Add ends
Quiz 1
3 Jan 31   Booleans
Zelle Sections 7.1, 7.2, 7.3, 8.4.1 (pg. 246-247)
Lab3: Decision statements
Feb 02  
Feb 04  
4 Feb 07 Quiz 2 Study Guide Graphics, Objects
Zelle Chapter 5 (skip 5.5, 5.6)
Notes on the Graphics Library
Lab4: Graphics
Feb 09  
Feb 11 Quiz 2
5 Feb 14   Functions, Objects
Zelle Chapter 6 (skip 6.3)
Lab5: Animating aliens
Feb 16  
Feb 18  
6 Feb 21 Quiz 3 Study Guide While Loops, More Functions
Zelle Sections 8.1, 8.2, 8.3
Lab6: The Rain Game
Feb 23  
Feb 25 Quiz 3
7 Feb 28   Top Down Design, File I/O
Zelle Sections 9.1, 9.2, 9.3, 4.6
Lab7: Mastermind
Mar 02  
Mar 04  

Mar 07

Spring Break

Mar 09

Mar 11

8 Mar 14   Searching, Analysis of Algorithms
Zelle Section 13.1
Mar 16  
Mar 18  
9 Mar 21 Quiz 4 Study Guide Sorting, Analysis of Algorithms
Zelle Section 13.3
Lab8: Searching and Sorting
Mar 23  
Mar 25 Last day to declare CR/NC or W
Quiz 4
10 Mar 28   Dictionaries
Zelle Section 11.6
Lab9: Did you mean...
Mar 30  
Apr 01  
11 Apr 04 Quiz 5 Study Guide Recursion
Zelle Section 13.2
Lab10: Recursion
Apr 06  
Apr 08 Quiz 5
12 Apr 11   Defining new classes
Zelle Sections 10.1, 10.3.1, 10.4
Lab11: Pong
Apr 13  
Apr 15  
13 Apr 18 Quiz 6 Study Guide Linked lists
Lab12: Choose your own adventure
Apr 20  
Apr 22 Quiz 6
14 Apr 25   Advanced Topics, Wrap-up
Apr 27  
Apr 29 Final Exam Study Guide

May 07

Final Exam, 2-5 p.m., SCI 101