# Comp Sci at Stuyvesant with D. Holmes

Content
Zoom steps for joining a remote session
coming soon Rocket.Chat server, for use during class sessions and for brief communications
notes notes by Holmes to augment some lessons, starting with a syllabus
hw Check for a new homework assignment after 3:30 on every class day.
coming soon Piazza forum, for communicating among students and instructor(s)
How to succeed with Piazza, especially for issues with homework
hw server for submitting homework answers. See these FAQs.

# homework teaches success

Students succeed in this course by understanding the homework. You are unlikely to learn new material at the pace of this course merely by attending class, even if that worked in middle school. Whether you judge success by mastery of the course material, or judge success by grades, understanding the homework is apparently required. To acquire that understanding, you must practice the thinking, look for patterns, find your errors, and revise erroneous attempts. Homework exercises all of those necessities.

Homework requires 20–30 minutes per day for a typical student in an introductory course, and up to 60 minutes per day in the advanced placement course. It commonly takes less for a student with experience in programming, but more for a student who is struggling or catching up.

There are six key elements to doing homework completely and correctly. These apply to many courses in high school and college:

• Struggle solo with a problem. When confronted by something they don't understand, beginning programmers should struggle on their own for at least 10 minutes, which initially feels like a very long time. More experienced programmers spend longer on their own, perhaps half an hour.

• Seek help but not answers for problems that remain. The best programmers seek help eventually; that helps makes them the best.

• Incorporate help to produce correct results. This means returning to "struggle solo", but armed with more knowledge.

• Test your work  A correct-looking solution that has not been tested is almost certainly wrong.

• Compare your work with posted solutions. If the posted solution leaves you with questions, ask them.

• Re-do parts of the homework based on your comparison. Merely reading correct answers leaves lots of us unable to create correct answers. So if the "compare" step shows that your initial understanding was faulty, and if the topic is at all interesting, shut any display of the right answers and recreate those answers yourself.

Tests in this course aim to assess the extent to which a student understands the homework. People motivated by grades can boost them via the do–compare–re-do sequence.

## keeping up is easier than catching up

Keeping up with homework assignments is challenging but crucial in computer science courses, for several reasons:

• Undone homework piles up. Many students find it challenging to fit each day's homework into full or over-full schedules, and skipping a day doubles the problem. Longer delays are many times worse.

• It is in doing homework that students actually learn the material presented in a day's class. The longer the delay between the presentation of the material and the homework, the less you remember from the class. It is easier to do Monday's homework at 4 pm than 11 pm. It is easier to do Friday's homework on Friday than on Sunday. Delays make homework harder.

• Here's the most important issue: understanding classes depends on your having learned previous classes' material, by doing the associated homework. Without that learning, succeeding classes can be worse than worthless to you, because they confuse you instead of teaching you. The confusion makes the next homework more difficult, in a rapid, downward spiral.

## homework omits repetition

In fifth grade, math homework typically involves many repetitions of similar problems. Students can learn by repeating similar work until patterns become obvious. Each problem requires only a minute to solve.

That model fails in problem-solving courses like this one, where the problems are larger. It can easily take 10 or 15 minutes to write a program, test it to find errors, and fix those errors. So an assignment that is aimed to take half an hour should require writing at most three such programs. Students can no longer rely on absorbing a pattern through repetition.

Instead, be thoughtful about the problems. Do the significant work that can be required to understand the question. Struggle solo with the solutions, rather than immediately asking for assistance. Write down questions that occur to you, and take the initiative and responsibility to seek answers.

## understand homework solutions

You are responsible for understanding solutions for homework problems, by reviewing answers to them. Students and I collaborate on posting answers, usually on Piazza. There are good reasons to study these solutions:

• You learn little from incomplete or erroneous homework. I lack the time to check your work routinely and completely. That responsibility devolves to you.

• Programmers learn by reading other programmers' work. I have learned that way for many years, with no end in sight. Posted solutions are imperfect and occasionally outright wrong, but one also learns from rejecting and correcting others' ideas.

• Learning from others' solutions is efficient. If you did the homework, it takes only a few minutes to compare your solutions to those posted, more if the solutions are better than yours, less if they are similar. If you failed to do the homework, reading others' solutions is slower and less educational, but still better than nothing.

## "My computer (or internet connection) broke, so I can't do the homework."

Computer failure happens to everyone eventually. I would like to express my sympathy by lifting the requirement to do homework while awaiting repair or replacement. But from the point of view of keeping up with the homework, a broken computer provides no relief from the problems of falling behind. Students must find a way to keep up. Here are some strategies:

• Do the homework with a classmate, on their computer. It is usually more educational and often more fun to work with a friend, even when your computer works. Of course, if you work with someone else on the homework, you must cite that cooperation in your submissions.

• Share a computer with a family member. Most homework requires only a browser and an installation of a processor for the relevant language (DrRacket, NetLogo, Python, or Java). Installing a language processor is straightforward. Modern operating systems allow a family member to establish a guest account that preserves their privacy while allowing a student to share the working computer.

• Go to the CS Dojo, where there are plenty of computers. Bring a pair of headphones or ear buds if the homework requires listening to Mr. Brooks's videos.

Whatever approach you take, rise to the challenge of keeping up while repairing your computer.

A broken internet connection requires similar thinking. You can use a computer at school, including those in the library and CS Dojo. You can submit homework by carrying it to school on a USB drive and submitting it from school.

## corrections on the homework server are shown as late submissions

The homework server records the time of the last submission for each homework slot. So if you submit homework on time, but subsequently submit a correction to it, the homework server will show the submission as late. That happens even if the correction is that you originally submitted the homework to the wrong homework slot, and you re-submit it to the correct slot.

Corrections are helpful. Correcting the content of homework is a great way to learn. Correcting which slot holds which homework helps me if I review it.

The apparent lateness is such a minor problem that you can ignore it. To keep the record straight, you can include a comment with the re-submission, telling me that the original was on time. But look at this from my perspective: I use the timeliness to alert me to students who are falling behind in the course, to spot where a conversation might be helpful. A rare lateness is harmless, so neither of us should spend much effort to avoid a rare appearance of lateness.

Re-submissions overwrite the comments from previous submissions. So if the existing comment has valuable information, copy it before re-submitting, and include the copy in the re-submission.

## rubric for homework

Homework is graded with a denominator of 3. The basic grades are…

• 3:  meeting expectations, on grade-level.
• 2:  missing a chunk
• 1:  missing several chunks
• 0:  no submission or submission without effort

For submissions that surpass expectations, there is a 10% bonus, resulting in a grade of 3.3

Late homework is worth 1 point less than a comparable on-time submission.

# how else to succeed

## recommendation: work with a classmate

Working on the homework with another student can help significantly. Some people mistakenly imagine that the benefit derives solely from sharing knowledge, but in addition…

• Working with another person fosters questions and answers. Verbalizing questions and answers fosters the hard thinking that is necessary for learning.

• Some people think more productively in company, as discussed here.

• The discipline of working with another person supplements the self discipline required to work alone. If you — like most of us — find it difficult to push away distractions and focus on work we want to accomplish, you may find it easier to make an appointment with a classmate to work together, ideally at the CS Dojo. Then your natural politeness and disinclination to abandon an appointment will augment your self discipline.

• For those of us who enjoy teamwork, working with others is more fun than working solo.

• Sharing knowledge is easier when working in pairs.

Stuy's CS teachers strongly encourage you to experiment and improve at working in pairs.

Some caveats:

• "Working on" homework is not the same as "copying" homework. Copying involves no thinking and helps little in computer science courses. You need not believe me; ask someone with bad grades who tried it.

• Academic honesty requires that you understand and be able to explain your submissions, and that you identify sources of help. For example, it is always a pleasure to read comments like "I worked with Brian Kernighan on this problem, and I completely understand the results." Submitting another's work without giving credit is cheating.

## keep up when you miss a lesson

As with homework, it is easier to keep up than catch up with the content of lessons. If you miss a day or are confused by a lesson, take remedial action quickly.

The best way to catch up is to sit with another student from your class to go over their notes, while taking notes yourself. Both of you are likely to benefit; a person who teaches learns from the process, clarifying their own thinking. (I know; I learn from this effect every day.)

The web page on "notes from class" shows some class materials. Those materials can augment or correct your recollection of what you heard in class. They lack topic questions and their answers, however, so you will need notes by a student.

## good students seek help

Too many Stuy students are reluctant to seek help, perhaps because middle school was easy for them. In better high schools and colleges, good students seek help; weak students don't.

Know these sources of help:

• Participants in this course will be enrolled in Piazza, a web forum in which students pose and answer questions, obviating the scheduling that would be required to meet with someone else. It has aided communication and learning for hundreds of thousands of students in colleges.

• Your classmates — especially those in classes I lead — have thought about and solved issues you face. Ask a few for their approach, pick one you can emulate, and practice it. Copying an effective technique is easier than inventing one.

• The Comp Sci Dojo meets four times weekly after school. There, successful comp sci students offer help in an environment conducive to doing comp sci homework. It happens Monday through Thursday in room 307, from 3:40-5:00. Bring your notes, plus a homework problem or test question on the topic of your confusion.

Even better, bring a classmate; both of you will learn more by working together, with your work augmented by occasional help from the mentors at the Dojo.

For many students, the best way to learn what transpired in a class they missed or which confused them is to work with a classmate at the Dojo. Notes taken by class members should provide topic questions and partial answers. Dojo mentors can provide backup and alternative explanations, even though mentors do not typically attend our lessons.

When I visit the Dojo, I usually recognize students there who are among the best in their classes, working in an environment that they have found fun and conducive to success. Try it.

• You can generally find me in room 301 when I am not teaching.

• ARISTA offers one-on-one peer tutoring in all subjects.

## class and community participation

Asking questions or proposing answers helps the askers and answerers. Asking helps askers because they do the hard thinking necessary to identify misunderstandings. Answering helps answerers because they do the hard thinking necessary to verbalize their understanding. In addition, participating in class helps participants stay engaged with the class. Both questions and answers help me assess how well concepts are being communicated.

Many students are initially reluctant to reveal their confusion. Such reluctance is understandable since no one likes being wrong. You can help: work on making class a hospitable environment for the ego-sacrifice of asking questions and proposing answers that could be wrong.

The Piazza on-line forum extends participation beyond the class time. Participating via Piazza is particularly valuable for people who are disinclined to speak during class.

## notes help, if used well

Each day, the lesson's aims are displayed as questions, which you are asked to record. Knowing the aims in advance helps you recognize the answers as the lesson covers them. If we both do our jobs well, you should be able to answer those questions after the class

Many Stuy students found notes superfluous in middle school. Material was presented slowly enough, and with enough repetition, that they learned it during class, with no need to refer back to it. However, as you progress through increasingly challenging education, eventually you will reach a level at which you can no longer get by on being a fast learner, because everyone in your class learns as fast as you do, and the pace of the class is sped up accordingly. At that level, learning requires thinking about the material after class, independently. Independent thinking requires recalling the material. Successful students take notes that aid that recollection.

But taking notes is a counter-productive distraction unless you review them soon after taking them. If you never review your notes, or if you store them un-read until the night before an exam, you are likely to learn more by listening and thinking hard during class, without the distraction of taking notes.

Apollo Robbins will convince you in 9 minutes that copying from the board interferes with learning, because you can't think about two things at once. Way cool.

To benefit from notes, good students re-examine them after classes, reminding themselves of the questions, and identifying the answers. Do the review and identification before you start the homework. That timing helps with the homework, because the homework aims to exercise the class's material.

The alternative is more work for less learning. There are often many ways to solve computer problems, and lessons often base new techniques on those taught previously. Homework after the later lessons aims to exercise the new learning. But students who have not reviewed a lesson forget it. Instead, such students try to apply old lessons to new problems. That involves more work than using the newly-taught techniques, and forsakes the opportunity to learn the new techniques.

Algebra students are often introduced to solving quadratic equations by factoring. Later, they are taught the quadratic formula, which is helpful when the solutions are fractions or complex numbers. Pity the student who ignores the aim of the lesson on the formula, and works hard on the homework trying to guess the factors of x2x–1=0. The effort will be fruitless and it won't help the student understand the formula.

In summary:

• Bring your notebook with you to do the homework, so you can start by reminding yourself of the material that the homework addresses.
• Use the new material from class to solve the homework problems, so that the new material becomes meaningful to you.

Probably you have been told how to succeed at reading comprehension under time pressure. Often the techniques include…

• Read the questions before the passage, so you will recognize the parts of the passage that merit attention.
• Answer the questions and move on.

Maybe that is "how to succeed at reading comprehension on a standardized test".
Certainly it is "how to fail at reading comprehension in computer science and math".

Comprehension in this subject requires multiple close readings. Here is a typical sequence for understanding a programming problem:

Successful students read differently in different subjects. I learned that only in grad school. Maybe you can learn it sooner. Teachers never told me this before then, presumably because lots of teachers are as ignorant as I was, and for a similar reason: a single reading style had long worked for me in the subjects I liked best, and I got by in the other subjects.

I aim to check my understanding of reading in other subjects with teachers in those subjects. You might also.

Students routinely complain that my writing is hard to read. I may be a particularly bad writer, but there is also another issue: reading computer science text requires serious concentration in every word. Two examples:

• When I answer tests written by another comp sci teacher, I have to the read each problem 2 or 3 times, even though I have already spent a long time thinking about constructing these kinds of problems.

• I asked a group of other comp sci teachers whether they needed multiple readings, and they looked at me as if they thought I was a bit dim just for asking the question. Unless you are much better at computer science than those teachers, imitate them.

Communication is hard. Readers must expect to do their share of the work.

## how to write

Problems posed in this course routinely ask for answers in good English sentences. The responses are routinely hard to read, often because they ramble, or constitute only sentence fragments, or lack antecedents for pronouns.

Problems posed in this course routinely impose word limits. Weak students routinely violate those limits.

Avoid these errors by drafting an answer on scrap paper. I cannot answer a hard question in a single draft; it is optimistic, prideful, or foolish for you to expect that you can.

Save words by omitting echoes of my question. For example, if asked "What advantages derive from clear writing?", it is redundant to start your answer with "There are many advantages to clear writing. For example, one should practice clear writing because...". See William Strunk Jr.'s widely-admired advice.

Students have taught me why they make these errors: writing a lot, quickly and poorly, succeeds in other courses. That approach fails in this course.

# Holmes's schedule

period activity
1 teaching 1intro
2 teaching 1intro
3 teaching 1intro
4 learning by attending Mr. Dyrland-Weaver's class
5 usually available
6 teaching 1intro
7 teaching 1intro
8 usually available
9 usually available
10 usually available
after school usually available

To make an appointment to talk in person, send email. Tell me…

• the topic(s) you want to discuss
• an estimate of the length of the meeting
• the date and period for two times when you can meet with me.

I will respond with whether I can meet then.

Courtesy requires keeping your appointments, or — second best — alerting me in advance if you intend to break an appointment.

I work in room 307. You can call me there in the periods when the schedule above shows "usually available". Do not call when I am teaching! Extension 3070

# email helps communication

Thought transference from your head to another's is difficult; help the reader by writing carefully. Use standard English, full sentences, verbs, paragraphs, courtesy, organized thoughts, re-reading, revision, spell-checking, and all the other tricks you know for communicating effectively.

Use the subject field of your email to maintain threads that bind related messages together, thereby distinguishing one conversation from others. Indicate content and purpose. A subject like "help!" is useless; it tells the reader nothing except that the author is too lazy to help the reader understand the issue. Expect bad results from telling the reader that.

1 1
2 2
3 3
6 6
7 7

Put your name in the message, perhaps by configuring your email client's display name.

The first sentence of your email should tell the reader why you are writing or what you want. It should answer the reader's implicit question, "Why should I make the large effort to understand the rest of this email?"

Business-related emails like ours should not start with "I hope you're having a nice day", nor any of its variants.

In subsequent paragraphs, provide background, explanation, or amplification.

People occasionally try other ways to communicate with me that work less well than the email accounts shown above. Avoid these:

• The Department of Education has created a separate email account for my use at the domain schools.nyc.gov. But it is inconvenient to use.

• The homework server has a facility for leaving comments about the homework. But do not rely on my seeing a comment you leave there, because I read only as many of those comments as time permits.

The main use I make of those comments is to understand how long an assignment took, and whether most commentators report success or puzzlement. I skim comments to acquire an overall impression.

So for best results when you want individual attention, use the appropriate email address from the list above.

Whitelist email from the domain @DavidMHolmes.net, telling your email program that email from that domain should not be considered junk or spam. You may find good advice by searching the web for
     whitelist
followed by the name of your email program, like
     whitelist gmail

# classroom routines

It is widely observed that time is the most critical scarce resource in a class is time. As a student, the scarcity rarely occurred to me; I just had to keep up. But in leading a class, the scarcity rankles constantly. Can we delve far enough into a question to understand why people find it interesting? How much easier will the homework be if more of it is done in pairs in class? What's so cool about tail recursion optimization, and why should I care?

So it is worth establishing routines that save time and disruption.

## start of class

Your objective at the start of each class is to create as quickly as possible a mental and physical state in which you are ready to contribute and learn. There are 3 elements:

• Readiness to make notes requires starting a new page in your notebook with the day's date, and having 2 writing utensils of different colors on the table.
• Stow all other belongings under the table, clearing the aisle between tables.
• Foster mental readiness by recording the day's must-ask questions then working on the start-of-class assignment. (a.k.a. the do-now)

Finish these steps by the time the late bell rings. Most sophomores have assimilated this timing; I make it explicit here to avoiding embarrassing anyone who has not been taught it yet.

I have sympathy for people who are only now jettisoning the impression from middle school that time before the late bell is free for socializing, because I remember making the transition. But the absurdity of this misconception becomes apparent if you think about college classes. For example, in the first year at a medium-sized university, I was privileged to hear David Wilkinson take time out from his widely-recognized work studying how background radiation supports the big bang theory to teach physics to beginners. And Burton Malkiel had just left President Ford's Council of Economic Advisers to teach Econ 101 to a few hundred first-years. When people like that take 50 minutes to explain what they think you should know, you don't squander the first three looking for a seat and a pencil. Students probably don't make it that far unless they have learned how to prepare to learn. My teaching falls far short of those teachers', but you can certainly operate at the level of their students.

The start-of-class assignment typically asks you to…

• read the must-ask questions you recorded for the previous class; and class's aims; and
• highlight the answers to those questions in your notes, using your contrasting-color writing utensil. Sometimes you will notice questions from the previous class that were left unaddressed. That happens because I post an ambitious list, but students' learning and questions determine the pace.

You are welcome — indeed, it is probably better — to work in pairs with an immediate neighbor, augmenting each other's notes and jointly identifying answers. If you missed the previous class, seeking help from a classmate is necessary, not just optional.

By this stage in your scholastic career you know the appropriate voice level for group work. As a rule of thumb, if I can distinguish your voice over your colleagues', you are too loud. Learn to murmur.

As adherents of the Cornell note-taking system [1] [2] know, the review contemplated here is actually too little too late. By the time they start college, good students develop the self-discipline to review notes without prompting. That review is most profitably done soon after each day's class. There is no do-now in college, no teacher-designed exercises to help students recall the context of the previous class. Instead, successful students do that review on their own initiative, on a schedule that works for them.

While you are in high school, learn about and experiment with study techniques. To help with that experimentation, I assign techniques, such as the beginning-of-class reviews. By the time you reach college, should have experimented with already-known learning techniques, and internalized the ones that work for you.

Start-of-class routines typically finish within 3 minutes of the late bell, depending on the opening assignment. Four minutes represents 10% of the class time, so you can appreciate the need for discipline.

I cannot address individual concerns before classes. At that time I am trying to start the class as speedily as possible, so attending to individual concerns would delay the entire rest of the class. If you need individual attention for less than a minute — for example, to add a signature to an absence note — wait until the do-now is under way. For longer conversations, make an appointment. Sometimes I can also talk after periods.

## arrive on time

Class begins at the late bell.

# absence

## yours

### partial day

I teach your course several times a day. Students who plan to miss a class can ask permission to attend one of the other classes.

### whole day

When you are absent, it is your responsibility to catch up. Ask a reliable classmate to review their notes with you. Ideally, do this at the CS Dojo, for access to more help if questions arise. I regret that I cannot afford the time to tutor individual students. One benefit of your accepting this responsibility is that I rarely need to object to a student's missing a class for musical or sports conflicts, or to make up a test in another subject, etc.

## mine

When I am absent, I usually post instructions in the class notes. Look there and remind your neighbors to do so.

# etiquette

## independent learning and showing off

Everyone is welcome to learn extra topics on their own, and to use it on homework or tests. One of the great aspects of computer science courses is that you can learn any amount more on your own, and benefit from it, whether the amount is small or large. Every semester there are a handful of students whose interest in the material leads them on, and it is a pleasure to see.

But in class and Piazza, don't introduce digressions that hurt — rather than benefit — the class as a whole. Independent learning is great, as long as it is, well, independent.

This kind of self-restraint is tougher than it sounds, since it is natural to want to show off extra learning. Showing off is unattractive as well as distracting. Instead, independent learners occasionally ask quick questions after class on material they have been studying on their own, without distracting anyone or showing off in the slightest. Sometimes I can help by pointing them to the appropriate piece of the manual.

The temptation seems particularly acute on the homework solutions that students are asked to post. The solutions should present the simplest possible answer to the homework problems, so as to help someone who was a little confused by the presentation in class. Introducing new material is likely to further confuse such a person. In one semester this kind of showing off rendered Piazza posts unusably dense for many students and me. Keep that from happening.

Rather than Piazza, you are encouraged to participate in public forums like the StackOverflow community, which is like Piazza for pros. No one there will think you are showing off, not least because the pros there are really impressive. Here, for example, is a posting on StackOverflow by a great Stuy student. The question was answered by Seth Tisue, who was then the lead developer of NetLogo! Also notice how polite most people are on StackOverflow, including both the student in the original posting, Mr. Tisue in his generous response, and the student again in saying "thank you". If only life were like this.

To burnish your reputation within the class in a positive way, I recommend answering questions, in class and on Piazza, without condescension or outside-the-syllabus material. You can help lots of people by writing high-quality, well-tested hints or answers to questions about the material.

Answering a question posed by another student is also very helpful. The questioner thereby hears the answer phrased differently from the way I might phrase it. That difference is valuable because the questioner was left confused by my original phrasing, so hearing different phrasing is a better bet to help them.

People who enjoy learning about computer science will feel rewarded by taking more comp sci courses at Stuy or participating in the comp sci community outside classes. The other classes and activities are led by people whose great teaching inspired me to want to join them. Both activities will give you the company of independent learners who are nice people, and who share your interests. Learning in the company of good students is why you went to Stuy, whether you knew that in advance or not.