Introduction

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:

• Given a problem, be able to design a clear, concise, and correct pseudo code algorithm to solve it.
• 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.
• 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 pseudo code algorithm, be able to successfully implement it in Python.
• 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.

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Class info (Spring 2010)

Room: Science Center 240
Time: MWF 11:30–12:20am
Required Text:

• (Z): Python Programming: an Introduction to Computer Science by John Zelle
  (Zelle is on reserve at Cornell Library)

Instructional staff

Professor: Doug Turnbull
Office: Science Center 255
Email: turnbull AT cs DOT swarthmore DOT edu
Phone: (610) 957-6071
Office hours: by appointment

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

Student Mentors: T.B.A.
Other Sections: Tia Newhall (MWF 9:30–10:20) | Lisa Meeden (Bio-Version, TTH 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 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, free food is often 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 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
2:30-4:00pm Monday	Newhall	Sci Center 240 (Main Lab)
3:30-5:00pm Monday	Meeden	Sci Center 240 (Main Lab)
1:00-2:00pm Friday	Turnbull	Sci Center 240 (Main Lab)

* if there's a campus collection, the Friday lab will be 2-3pm

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Schedule

Grading

Grades will be weighted as follows:

40%	Lab assignments
30%	Quizzes
5%	Class Participation
25%	Final Exam

Lab and Homework policy

Programming assignments will typically be assigned in class at the beginning or 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 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

• 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 lab exercises. 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, attend the study sessions, come talk with me during my office hours, or email me your question.
• Start the lab 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 lab projects. 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 CS21 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 lab assignments.
• Work with a partner.
  Several of the assignments will optionally allow you to work with a partner. This is highly recommended. Working in groups can help you progress further through the assignment more quickly. Partners can often catch silly coding mistakes that may leave you frustrated for hours if working alone. Explaining concepts and ideas to a partner is a great way to help you learn the material and clarify your thinking. If you are interested in working with a partner but do not know who to ask, contact me and I can try to pair you up with a compatible student.
• Patience
  Programming can be frustrating when the computer doesn't do what you want it to do. When this happens take a deep breath or walk way from it so that you can return with a clear head.

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:
  • description of what function does
  • description of input parameters
  • description of return value or values
• 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 example of good style.

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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.

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 normally is 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." - Student Handbook (2009-2010, pg18 Section I.B.3.b.i)

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

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External Links

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
How To Think Like a Computer Scientist: Python for Software Design
Zelle Textbook site
Dive Into Python
(A Semi-Official) Python FAQ Zone
NodeBox (for Mac OS X)
pythonchallenge