Course Information

Section 3: TR 09:55 – 11:10 SCI 256
Professor: Grace Ngai
Piazza: Question and answer forum for the class
Office: SCI 251
Phone: I hate the phone – send me email
Office hours: Tuesday 14:30-15:30, or drop in, or by appointment

Introduction

Welcome to cs21. This course will introduce fundamental ideas in computer science while also teaching you how to write computer programs. You will study algorithms for solving problems and learn how to implement solutions in the Python programming language. 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 how to 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 either cs31 or cs35.

Textbook

There is no required textbook for this course. There are, however, required readings! See the Schedule for each week's reading assignment. We will primarily be using the online book How to think like a computer scientist: Learning with Python by Elkner, Downey and Meyers.

Here are a few other useful online python resources:

• The Python tutorial
• Python documentation (Note: we are using v2.7)

Goals for the course

• Given a program, be able to simulate on paper on 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.
• Give 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 and consistently used these skills when implementing programs.

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Grading Policies

Grades will be weighted as follows:

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

Lab Policy

This course features weekly lab assignments which are the largest component of your course grade. Lab attendance is required by all students, unless you have already completed and submitted the lab assignment for the week. You must attend the lab session for which you are enrolled:

Weekly Lab Sessions
Lab A: Tues. 1:05—2:35pm	Knerr	Science Center 256
Lab B: Tues. 2:45—4:15pm	Knerr	Science Center 256
Lab C: Thur. 1:05—2:35pm	Ngai	Science Center 240
Lab D: Thur. 2:45—4:15pm	Meeden	Science Center 240

Lab assignments will typically be posted on the web by Sunday afternoon and will be due before midnight on Saturdays. 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, and a history of previous submission will be saved. You are encouraged to submit your work regularly.

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.

Quiz Policy

Quizzes will be given at the beginning of class on the days posted in the Announcements section of the Schedule. Please look at these dates carefully and contact me in advance if you cannot be in class for a quiz.

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Academic Integrity

Academic honesty is required in all of your work. Under no circumstances may you hand in work done with (or by) someone else under your own name. 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, but is not limited to, obtaining solutions from students who previously took the course or code that can be found online. You may not share solutions after the due date of the assignment. However, 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.

All code you submit must be your own with the following permissible exceptions: code distributed in class, code found in the assigned readings for the course, 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.

Failure to abide by these rules constitutes academic dishonesty and will lead to a hearing of the College Judiciary Committee. According to the Faculty Handbook: "Because plagiarism is considered to be so serious a transgression, it is the opinion of the faculty that for the first offense, failure in the course and, as appropriate, suspension for a semester or deprivation of the degree in that year is suitable; for a second offense, the penalty should normally be expulsion." Be aware that we will be routinely running plagiarism detection software on the lab solutions of students from all sections of cs21.

Please contact me if you have any questions about what is permissible in this course.

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Student Support

Lauri Courtenay is the CS Department's Academic Support Coordinator. She will be working closely with our student mentors, also known as Ninjas, to help you learn how to program and think like a computer scientist. The Ninjas for this semester are: Isabel (Izzi) Baskin, Alexander Simms, Afua (Dee) Ahima, Allison Ryder, Daniel Redelmeier, and Justin Cosentino.

Study sessions

You are invited, and encouraged, to participate in Ninja evening 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 snacks will be provided at the sessions. The sessions are held:

Weekly Evening Ninja Sessions
Mondays	7—9pm	Sci Center 256
Thursdays	7—10pm	Sci Center 256

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, 240, and 256.

Academic Accommodations

If you believe that you need accommodations for a disability, please contact Leslie Hempling in the Office of Student Disability Services (Parrish 113) or email lhempli1@swarthmore.edu to arrange an appointment to discuss your needs. As appropriate, she will issue students with documented disabilities a formal Accommodations Letter. Since accommodations require early planning and are not retroactive, please contact her as soon as possible. For details about the accommodations process visit Student Disability Services.

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Tips for Success in cs21

• 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 before 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 study sessions, come talk with me during my office hours, or post your question on Piazza.
• 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 quizzes and final exam 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 labs and study sessions
  Lab attendance is required. 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.

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Schedule

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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 value(s) (parameter values); (3) description of return value
• Well organized code
• White space or comments to improve legibility
• Avoidance of large blocks of copy-pasted code