CS21 — Intro. to Computer Science

Announcements | Schedule | Grading | Study Sessions | Succeeding | Style | Integrity | Links
Introduction to Computer Science using Python



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 CS35. If you have no prior computer science or programming experience, this course is designed for you.

Goals for the Course

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

Class info

Room: Science Center 240
Time: TR 9:55–11:10am
Text: Python Programming: an Introduction to Computer Science by John Zelle

Instructional staff

Professor: Andrew Danner
Office: Science Center 253
Phone: (610) 328-8665
Office hours: by appointment

Student Support: Betsy Horner
Office: Science Center 255
Email: bhorner1
Phone: 957-6062

Student Mentors: Maria Kelly, Amanda Morrison, Ashley Oudenne
Other Section: Richard Wicentowski (MWF 10:30–11:20am)

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
Sunday 7:00–9:00pm Sci Center 240
Wednesday 7:00–9:00pm 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. Please bring your textbook to the study session. A limited number of copies (sometimes just one!) are available in the lab.

Weekly 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 main CS labs to help CS21 students with their lab assignments. 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 session.
Time Professor Location
Monday 2:00–3:30pm Wicentowski Sci Center 240
Monday 3:00–4:30pm Danner Sci Center 240


1 Jan 20   Introduction to Python and Unix
Chapt. 1-2
in class
Lab 0
Lab 1
Jan 22  
2 Jan 27 Practice Quiz 1 PDF Numbers and Strings
Chapt. 3-4 (Skip 4.6)
in class
Lab 2
Jan 29 ASCII table
Drop/add ends (Jan 30)
3 Feb 03   Booleans
Chapt. 7
in class
Lab 3
Feb 05  
4 Feb 10 Practice Quiz 2 PDF Graphics, objects
Chapt. 5
in class
Lab 4
Feb 12  
5 Feb 17   Functions, objects
Chapt. 6
in class
Lab 5
Feb 19  
6 Feb 24 Practice Quiz 3 PDF Loops, Top Down Design
Chapt. 8, 9
in class
Lab 6
Feb 26  
7 Mar 03   Top Down Design, Loops
Chapt. 8, 9
in class
Lab 7
Mar 05  

Mar 10

Spring Break

Mar 12

8 Mar 17 Practice Quiz 4 PDF Searching, Analysis of Algorithms
Chapt. 13.1
in class
Lab 8
Mar 19  
9 Mar 24   Recursion, Sorting
Chapt. 13.2-13.3
in class
Lab 9
Mar 26  
10 Mar 31 Practice Quiz 5 PDF More Recursion, More Sorting
Chapt. 11.6
Lab 10
Apr 02  
11 Apr 07   Dictionaries Lab 11
Apr 09  
12 Apr 14 Practice Quiz 6 PDF Defining new classes
Chapt. 10
Lab 12
Apr 16  
13 Apr 21   Object Oriented Design
Chapt. 12
Lab 13
Apr 23  
14 Apr 28 Practice Quiz 7 PDF Linked lists
Lab 14
Apr 30  

May 15

Finals Exams 7pm-10pm Sci 199


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 may submit what you have done to receive partial credit.

How to Succeed in CS21

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 example of good style.

Academic Integrity

Academic honesty is required in all work you submit to be graded. You may not submit work done with (or by) someone else. You may not examine or use work done by others to complete your own work. 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 the student mentors and your partner on group assignments, you may not work with others on your assignments.

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 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.

"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.

Vi Quick Reference
Python style guide From Prof. Tia Newhall
Using Unix Improved
Basic Unix Commands
Python Documentation
Textbook site
How To Think Like a Computer Scientist: Learning with Python