Class Info

Section 1: TR 11:20–12:35, Sci Cntr 240
Professor: Tia Newhall
email:
Office hours: Thurs 3-4pm, Sci Cntr 249

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.

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Student Support

Student Support Coordinator: Betsy Horner (office: 257 Sci Ctr phone: x6062)

CS21 Ninjas (student mentors): Maria Kelly, Sarah Chasins, Frank Chien, John Dinh, Rachel Lee

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
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.

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 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 2:30-4:00	Danner	Science Center 240
Mondays 3:30-5:00	Newhall	Science Center 240
Fridays 1:00-2:00*	Knerr	Science Center 256 (the robot lab)

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

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

• Attend class.
  The primary introduction to course material is through class lecture. 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.
• 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.
• Ask questions if you don't understand.
  This means both during class and while doing lab assignments . 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 "Academic Integrity" section below first), attend the lab and 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 labs. 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 Labs and Study Sessions.
  The student 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. The CS 21 professors hold lab sessions each week. You are encouraged to attend these to get help with lab assignments.

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.

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Grading

Grades will be weighted as follows:

40%	Homework assignments
30%	Quizzes
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.

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Schedule

There is no required text for this course, however, if you would like a reference, here are two we recommend (the weekly schedule lists related material from both):

• (D): Think Python: How to Think Like a Computer Scientist by Allen B. Downey
• (Z): Python Programming: an Introduction to Computer Science by John Zelle
  (Zelle is on reserve at Cornell Library and there are a few copies available to use in CS lab)

WEEK	DAY	ANNOUNCEMENTS	TOPIC & REFERENCES	INCLASS & ASSIGNMENTS
1	Sep 01	Using Unix (240 SciCntr): Tues: 4-5pm Wed: 7-8pm Thur: 7-8pm	Introduction to Python and Unix Chapt. 1-2 (Z), Ch. 1-Ch. 2 (D) getting started guide: Python and Unix for lab assignments	In class: Tues In class:Thurs Assn: lab 0 Assn: lab 1
	Sep 03
2	Sep 08	practice quiz 1	Numbers and Strings Chapt. 3-4 (Z), Ch. 2 (D)	In class: Tues In class:Thurs Assn: lab 2
	Sep 10	Add/Drop ends Friday (Sep 11)
3	Sep 15		Booleans Ch. 7 and p. 247 (Z), Ch. 5.1-5.7 (D)	In class: week3 Assn: lab 3
	Sep 17
4	Sep 22	practice quiz 2	Graphics, objects Chap. 5(Z) READ THIS! notes on the Graphics Library	In class: week 4 Assn: lab 4
	Sep 24
5	Sep 29		Functions, objects Chapt. 6 (Z), Ch. 3, Ch. 6 (D)	In class: week5 Assn: lab 5
	Oct 01
6	Oct 06	practice quiz 3	while Loops, More Functions Notes on strings and lists as objects Notes on using the random library Chapt. 8, 9 (Z), Ch. 7 (D)	In class: week 6 Assn: lab 6
	Oct 08
	Oct 13	Fall Break
	Oct 15
7	Oct 20		Top Down Design, File I/O Chapt. 9, 4.6 (Z), Chapt. 14, Ch. 14 (D)	In class: week 7 Assn: lab 7
	Oct 22
8	Oct 27	practice quiz 4	Searching, Analysis of Algorithms Chapt. 13.1 (Z), Chapt. 9 (D)	In class: week 8
	Oct 29
9	Nov 03		Sorting, Analysis of Algorithms Ch. 13.2-13.3 (Z) 9 (D)	In class: week 9 Assn: lab 8
	Nov 05
10	Nov 10	practice quiz 5	Recursion Chapt. 13.1-13.3 (Z), Ch. 5.8-5.10	In class: week10 Assn: lab 9
	Nov 12
11	Nov 17		Defining new classes Chapt. 10 (Z), Chapt. 15-17 (D)	In class: week 11 Assn: lab 10
	Nov 19
12	Nov 24		Object Oriented Design Chapt. 12 (Z), Chapt. 15-17 (D)	In class: week 12
	Nov 26	Thanksgiving Break
13	Dec 01		Linked lists handout	In class: week 13
	Dec 03
14	Dec 08		Wrap-up	In class: week 14
	Dec 10
	Dec 17	Final Exam (7-10pm)

External Links

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

• Getting started with python and Unix
• running update21 and handin21
• Useful Unix commands: similar to handout from the first day of class.
• vim reference
• My Unix Documentation editors, email, protecting/sharing files, Python programming guide, ...
• CS dept. help pages (that includes the Using Unix Tutorial)

• Python Code Style Guide
• Python Links
• Python Tutorial from python.org This tutorial covers some parts of the python language that we will not cover in class, so use this as a reference for the parts we do cover and don't worry about the parts we don't. Also, if you start out at the python.org website, make sure that you look at reference material for version 2.X or 2.6 of python (this is the version we are using).