- Lab 12 is available. This is an
optional lab using dictionaries, and provides a good way for you to
review many of the topics covered this semester.
- The final exam will be Sunday, May 13, from 2-5pm in SCI 101.
- The final exam study guide is available. There will be two review sessions, both in SC 256: Wednesday, May 9 from 2-3:30pm and Friday, May 11 from 12:30-2pm.
Jump to this week
MWF 9:30–10:20, Sci 256
Professor: Ameet Soni
Office: Sci 253
Office hours: Thursdays, 2-4pm
In class polling: pollev.com/ameetsoni277
MWF 10:30–11:20, Sci 256
Professor: Lila Fontes
Office: Sci 258
Office hours: Thursdays, 10am-noon
In class polling: pollev.com/lilafontes615
Tu/Th 09:55–11:10, Sci 256
Professor: Lisa Meeden
Office: Sci 243
Office hours: Wednesdays, 1:30-3:30pm
In class polling: pollev.com/lisameeden929
Lab Instructor: David Mauskop
Office: Sci 262A
Office hours: Thursday, 3-5pm
Piazza: CS21 Q&A forum
Links to all sections:
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 CS31 or CS35.
We will primarily be using the online book
How to think like a computer scientist: Learning with Python
by Elkner, Downey and Meyers.
See the Schedule
for each week's reading assignment.
Here are a few other useful online resources:
Goals for the course:
By the end of the course, we hope that you will have developed the
- 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
- Develop debugging and unit testing skills. Consistently use
these skills while implementing programs.
Here are the tentative schedules for each section:
Grades will be weighted as follows:
Exam and Quizzes
Quizzes will be given at the
beginning of class on the days posted on
the Schedule. Please look over these
dates carefully and contact the professor in advance if you cannot be
in class for a quiz.
If you are not present on the day of a quiz, and do not let me know ahead
of time that you are missing class, you will receive a zero for that quiz.
There will be one final exam for the semester. Details and dates will be released during the semester.
Please read the section on accommodations if you are in need of extra time.
You must inform me of accommodations or conflicts at least 2 weeks in advance of the exam.
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
|CS21 A 1:05—2:35pm Tuesdays
|| David Mauskop
|| Sci 240
|CS21 B 2:45—4:15pm Tuesdays
|| Lisa Meeden
|| Sci 240
|CS21 C 1:15—2:45pm Wednesdays
|| Lila Fontes
|| Sci 256
|CS21 D 3:00—4:30pm Wednesdays
|| Ameet Soni
|| Sci 256
Lab assignments will typically be assigned in class at the
beginning of the week and will be due before midnight on Saturdays.
You are strongly encouraged to start early and to attend the
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 are not accepted and will receive zero credit (see exceptions below).
Even if you do not fully complete an assignment, you should submit what you have done to receive partial credit.
The CS labs are open 24 hours a day, 7 days a week for you to use for CS21 lab assignments.
If you feel that you need an extension on an assignment or that you
are unable to attend class for two or more meetings due to a medical
condition (e.g., extended illness, concussion, hospitalization) or other
emergency, you must contact the dean's office and your instructors.
Faculty will coordinate with the deans to determine and provide the
appropriate accommodations. Note that for illnesses, the
College's medical excuse policy,
states that you must be seen and diagnosed by
the Worth Health Center if you would like them to contact your class
dean with corroborating medical information.
Academic honesty is required in all 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.
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. All code you submit must be your own
with the following permissible exceptions: code distributed in class,
and code found in the course text book. 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.
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 CS21 Ninjas will assist me in class and run evening
study sessions in the birds' nest (Sci 256). The
Ninjas (student mentors) are: Anya Chaudhri, Christina
Holmgren, Tristan Cates, Jeff Novak, Shayne Rothman, Zachary Viscusi,
Michael Kourakos, Haochen Wang, Daniel Chaiken, Bayliss Wagner, Tai
Thonghai, Yash Kewalramani.
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
||Sci Center 256
||Sci Center 256
||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
next to the lab doors. When the green light goes on, just push the door 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 firstname.lastname@example.org (or see Bridget)
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
If you believe that you need accommodations for a disability, please
contact the Office of Student Disability Services
(Parrish 113W) or email studentdisabilityservices
to arrange an appointment to discuss
your needs. As appropriate, the Office will issue students with documented
disabilities a formal Accommodations Letter. Since accommodations
require early planning and are not retroactive, please contact the Office as
soon as possible. For details about the accommodations process,
Student Disability Service
To receive an accommodation for a course activity, you must have an Accommodation
Authorization letter from the Office of Student Disability Services and
you need to meet with me to work out the details of your accommodation at least one
week prior to the activity.
You are also welcome to contact me privately to discuss your academic needs.
However, all disability-related accommodations must be arranged through
the Office of Student Disability Services.
How to Succeed in CS 21
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
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 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 quizzes 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.
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.
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
- Meaningful variable and function names
- Function comments that include:
- description of what function does
- description of input value(s) (parameter values)
- description of return value
- Well organized code
- White space or comments to improve legibility
- Avoidance of large blocks of copy-pasted code
This semester we’ll be using
Piazza, an online Q&A forum
for class discussion, help with labs, clarifications, and
announcements that pertain to all sections of cs21.
You should have received an email invitation to join
CS21 on Piazza.
If you didn't, please let us know.
Piazza is meant for questions outside of regular meeting times such as
office hours, ninja sessions, class, and lab. Please do not hesitate to ask
and answer questions on Piazza, but keep in mind the following guidelines:
- Piazza should be used for ALL content and logistics questions outside of
class, lab, office hours, and ninja sessions. Please do not email
instructors or ninjas with your code or questions about the assignments.
- If there is a personal issue that relates only to you, please email your
- We encourage non-anonymous posts, but you may post anonymously (to your
classmates, not the instructors).
- Do NOT post long blocks of code on Piazza - if you can distill the
problem to 1-2 lines of code and an error message, that’s fine, but try to
avoid giving out key components of your work.
- By the same token, when answering a question, try to give some guiding
help but do not post code fixes or explicit solutions to the problem.
- Posting on Piazza counts toward your participation grade, both asking
Links that are related to the course may be posted here. If you have suggestions for links, let me know.
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