CS21:Intro to Computer Science, Fall'08

Class Info | Schedule | Study Sessions | Tips for Success | Grading | Style | Integrity | Links


Exam Review Session: Wednesday Dec. 17th, from 7-8pm in CS Lab


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 CS 33 or CS 35.

Goals for the course

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

  • Given a program, be able to simulate on paper how a computer would execute the program, and show the results that would be produced.
  • Given a problem, be able to design a clear, concise, and correct pseudocode algorithm to solve it.
  • Given a pseudocode algorithm, be able to successfully implement it in Python.
  • Be able to use top-down design to sub-divide a large problem into reasonably-sized modular sub-problems.
  • Given several algorithms for solving the same problem, be able to analyze which algorithm would be more efficient in terms of running time.
  • Develop debugging and unit testing skills. Consistently use these skills while implementing programs.
  • Learn to work as part of a team to solve problems starting from design and continuing through to implementation.

Class info

Room: Science Center 240
Time: MWF 9:30am–10:20am
Text: Python Programming: an Introduction to Computer Science by John Zelle

Instructional Staff

Professor: Tia Newhall
Office: Science Center 249
Phone: (610) 690-5637
Office hours: Monday 3:30-4:30: robot lab (252), W: 2-3: 249 Sci Center

Student Support: Betsy Horner
Office: Science Center 257
Phone: (610) 957-6062

Student Mentors (Ninjas): Celeste Abou Negm, Jake Baskin, Maria Kelly, Ashley Oudenne, Joel Tolliver

Study sessions

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

Day Time Location
Sundays 7-9pm Sci Center 240
Wednesdays 7-9pm Sci Center 240

You are invited -- and 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.

CS21 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 one of the CS labs (either 240 of 252 at the times listed below) to help CS21 students with their lab assignements. You are not required to attend any of these sessions, but you should take advantage of them to get assistance with your lab assignments. Any CS21 student is welcome to attend any/all session.

Time Professor Location
Mondays 3:30-5:00 Newhall Science Center 240
Mondays 4:00-5:30 Danner Science Center 240
Fridays 2-3 Knerr Science Center 252

How to Succeed in CS 21

  • Read the material before you come to class.
    Don't worry about total comprehension, but at least get a feel for what we will be covering that week. If you have some understanding of the material coming into class, it will be easier for you to ask questions during class, rather than later when help may not be available. Additionally, we often do lab exercises during class. This is an important part of the learning process, as these exercises give you immediate experience with the material we are covering. If you read the book before you come to class, you'll be able to complete these exercises more easily.
  • Ask questions if you don't understand.
    This means both during class and while doing your homework. This class continually builds on previous material, so if you don't understand something one week, it will continue to be a problem the next week, and the week after that, and so on. If you need help, ask your classmates (make sure you have read the "Homework Scenarios" section below first), attend the study sessions, come talk with me during my office hours, or email me your question.
  • Start the homework assignments early.
    I realize this one is not always easy to do, but if you can get in the habit of doing this, you will be much better off. If you get stuck early (i.e., not two hours before it is due), there will be time to look for help. In addition, if you start early enough, you can take a break, go do something else, and come back later. I find I always have at least a few new ideas when I come back to a problem after a break. If you wait until the last minute, you can't do this.
  • Practice, practice, practice.
    The only effective way to learn the material and pass the quizes and exams is to consistently do the homework. Finish all of the assigned programs (and do some extras, for fun!). Even if you don't get them done on time, they will still help you learn the material.
  • Seek help early and often.
    Because course material builds on previous material, it is essential to your success in this class that you keep up with the course material. If you are having difficulty with a programming assignment, if you didn't follow something covered in lecture, if you feel you need some extra help understanding or practicing some of the course material, or if you just want to discuss something from a lecture, an assignment, or the text, please come to my office hours.
  • Attend CS21 Study Sessions.
    The CS 21 Student Mentors (Ninjas) hold evening study sessions each week. You are encouraged to participate in these sessions. The Ninjas will help you prepare for quizzes, will provide additional instruction in programming concepts, and will provide friendly assistance on your homework assignments.


1 Sep 01 Using Unix: Tues 8pm CS Lab Introduction to Python and Unix
Chapt. 1-2
In class: Mon, Wed, Fri
Assign: lab 0
Assign: lab 1
Sep 03 Using Unix: Wed 7pm CS Lab
Sep 05  
2 Sep 08   Numbers and Strings
Chapt. 3-4, skip 4.6
In class: Mon, Wed, Fri
Assign: lab 2
Sep 10  
Sep 12 Add/Drop ends
Practice Quiz (pdf)
3 Sep 15   Booleans
Chapt. 7, plus p.247
In class: Mon, Wed, Fri
Assign: lab 3
Sep 17  
Sep 19  
4 Sep 22   Graphics, objects
Chapt. 5
The Graphics Library
In class: week4
Assign: lab 4
Sep 24  
Sep 26 Practice Quiz (pdf)
5 Sep 29   Functions, objects
Chapt. 6
In class: week5
Assign: lab 5
Oct 01  
Oct 03  
6 Oct 06   Loops, Top Down Design
Chapt. 8, 9
Notes on strings and lists as objects and random library
In class: week 6
Assign: lab 6
Oct 08 Practice Quiz (pdf)
Oct 10  

Oct 13

Fall Break

Oct 15

Oct 17

7 Oct 20   Top Down Design, File I/O
Chapt. 9, 4.6
In class: Mon,Wed,
Fri: top-down design

Assign: lab 7
Oct 22  
Oct 24  
8 Oct 27   Searching, Analysis of Algorithms
Chapt. 13.1
In class: Mon,
Wed, Fri
Assign: lab 8
Oct 29 Practice Quiz (pdf)
Oct 31  
9 Nov 03   Recursion, Sorting
Chapt. 13.2-13.3
In class: Mon, Wed
Assign: lab 9
Nov 05  
Nov 07 last day to withdraw from fall course
10 Nov 10   More Searching, Sorting and Recursion
Chapt. 13.1-13.3
In class: week10
Assign: lab 10
Nov 12 Practice Quiz (pdf)
Nov 14  
11 Nov 17   Defining new classes
Chapt. 10
In class: week 11
Assign: lab 11
Nov 19  
Nov 21  
12 Nov 24   Object Oriented Design
Chapt. 12
In class: week 12
Assign: lab 12
Nov 26  

Nov 28

Thanksgiving Break

13 Dec 01   Linked lists
In class: week 13
Assign:lab 13
Dec 03 Practice Quiz (pdf)
Dec 05  
14 Dec 08   Wrap-up In class: week 14

Dec 19

Final Exam (2pm-5pm) room Sci Ctr 101


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

Homework policy

Programming assignments will typically be assigned in class at the beginning 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 not be accepted except in extreme situations and only if you contact me before the deadline. 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:

  • A comment at the top of the program that includes
    • Program authors
    • Date or Dates
    • A brief description of what the program does
  • Concise comments that summarize major sections of your code
  • Meaningful variable and function names
  • Function comments that include: (1) description of what function does; (2) description of input values (parameter values); (3) description of return value(s)
  • Well organized code
  • White space or comments to improve legibility
  • Avoidance of large blocks of copy-pasted code
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 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.

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