The Magic of the Blackboard | Hacker News Reader

The Magic of the Blackboard

nautil.us

54 pointsdnetesn62 comments

Handouts and pdf files are poor ways to learn. Copying the blackboard onto paper with a pen as the prof scribbles on it is a much better way.

Technology has not improved on the blackboard at all.

The best presentation I've ever done was when the scheduled presenter never showed up. I volunteered. Having no slides, no preparation, I was faced with a white board and a dry-erase pen. Somehow, magic ensued.

I've never felt that way with prepared slides and a video screen.

I disagree. Based on my uni experience classes with handouts and pdf files was where I learned the best. The problem with blackboard is that professors go faster than you copy and it ends up being that spend all your time trying to copy everything that you don't have time to even listen to the words that they are saying. And when you try to review the scribbles in your notebook it's hard to understand anything. A good set of slides with examples and annotations goes a long way. And to this day I have slides I saved that I still refer to.

I HATED classes taught on a blackboard. I learnt nothing. Blackboard and chalk pedagogy is a technological artifact from the days it was economically infeasible to provide students with printed handouts.

The blackboard is a much more democratic, transparent, two-way tool: everything the teacher does the student can directly see and imitate. Watching someone reason with a writing implement in hand is an incredibly valuable learning exercise, since effective technical problem solving is largely done that way in practice. Students should also be practicing solving problems directly at the blackboard, with the teacher and other students as an audience. (Writing on an overhead projector or some kind of projected ipad screen or something could be an alternative, but these are higher-tech for no real advantages in an in-person lecture context, and make it much harder for multiple people to participate together. Writing on paper is an okay substitute if there are no more than about 3–4 students per teacher.)

A handout or slides or video is an opaque one-way tool, a prepared polished document that students can see but typically have no easy way to imitate. It affords the lecturer more chance to put effort in up front into making a clearer document, but robs students of the chance to witness their teacher doing some of the work in real time, and ultimately leads to a relative loss of basic problem solving skills involving writing/drawing, trading them away in favor of immediate gratification. Sometimes this trade-off is worth it (e.g. Grant Sanderson's work largely couldn't be replaced by blackboard lectures https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw ), but when the school's entire pedagogy moves that way, the loss is tremendous in my opinion, an erosion of some core tools of a centuries-old mathematical/scientific culture.

> Watching someone reason with a writing implement in hand is an incredibly valuable learning exercise, since effective technical problem solving is largely done that way in practice.

I vehemently disagree. Classroom lectures almost always present results that are already in the bag. I can't remember a single class where a professor actually walked us through the process of figuring something out. The closest I've ever seen is 3blue1brown, and he obviously doesn't use a chalk board.

Nowadays technical problems are often solved by writing code, which is almost never done on a chalk board outside of job interviews.

Even when chalkboard lectures present material that was prepared in advance, there's a significant difference vs. prepared material presented in slides or a typeset document or a video. Writing imposes a speed limit on the lecturer, and forces them to verbalize the whole reasoning process. In slides it is much easier to skip past the meat of the work, and much harder to be responsive in writing/pictures to questions and discussion.

> can't remember a single class where a professor actually walked us through the process of figuring something out

This can't really be blamed on the tool of the chalkboard. I promise you this does happen in some classrooms. It certainly happens all the time in informal discussion between professionals. In my opinion schools should strive much harder to induct students into a problem-solving culture than teach specific content trivia. A blackboard is an invaluable tool for the former.

> often solved by writing code

Writing code is a narrow and constrained tool with much less freedom than writing on paper, and thoughts made first in code are substantially blinkered in my experience compared to thoughts worked through on paper. Many of the best programmers I know do their most important work on paper (sketching, planning, doodling, drawing diagrams, ...) before ever touching the keyboard. And that is far more true still for mathematicians, physicists, etc.

What is true is that many programmers are not very effectively taught to use paper to its full advantage as a tool for thought, and either never learn or largely figure it out on their own. Our typical computer science pedagogy is frankly terrible at this, and professionals' on-the-job training isn't much better.

>> can't remember a single class where a professor actually walked us through the process of figuring something out

> This can't really be blamed on the tool of the chalkboard.

That is true, of course, but that was not the point. The point is that blackboards do not necessarily produce, or even encourage, good pedagogy. The two things are largely orthogonal.

> Writing code is a narrow and constrained tool with much less freedom than writing on paper

Yes, I think this is a feature, not a bug. It enforces a certain amount of rigor that blackboards don't.

Of course, the language in which the code is written matters a lot.

> I can't remember a single class where a professor actually walked us through the process of figuring something out.

I'm sad for you. All my professors did that in every lecture. I'd copy it down in a spiral notebook as he'd describe it step by step. Later, when reviewing the notes, it would bring back the lecture in my head.

This was before the days of videotape, but I still regret not taping the lectures with a cassette recorder.

Just to be clear, they did walk us through the process of solving the kinds of problems that would be on the final exam. But the starting point was always a set of equations that were simply given as gospel with no motivation nor justification nor hint as to how they were arrived at. It drove me nuts.

You can see this happening today. My favorite contemporary example is elliptic curves, which are a hot topic. Most introductory materials on elliptic curves will tell you that an elliptic curve is defined by an equation of the form: y^2 = x^3 + ax + b. Where did that come from? Why is there no x^2 term? How did anyone ever figure out that this particular equation would be good for cryptography? What other polynomial equations might be good for cryptography?

And then one day you learn about Montgomery curves, which do have an x^2 term but no x^0 term. So was the whole x^3 + ax + b thing a lie from the beginning? What about a complete cubic equation with all terms included? Is that an elliptic curve? Is it useful for cryptography?

Maybe my brain is just wired differently from most people, but those kinds of questions just pop up naturally for me, but I hardly ever see them either asked or answered. And this is true in every technical field I have ever studied, and I've had a very long and diverse career.

Those are very valid questions, and as a (former) professor, I know that most smart (and many 'not smart') students do ask those questions. Lecturers should do their best to set up the motivation for each topic. This can fail because

- There is not enough time. Unfortunately, formal courses have a fixed time, and the lecturer has to cover a certain amount of content in that time [1].

- Sometimes, its not actually possible to answer the 'why' questions with the amount of background that students have (or the lecturer has).

The above is also true for books/written down notes as well. For instance, in your example of elliptic curves, the answer to your questions about "why the form y^2 = x^3 + ax + b" requires students to understand algebraic geometry first, where such curves are defined in general (over arbitrary fields etc), rather than over the real field as you have. If you read such a book, you will see why in the general setting, its completely natural to define such curves. I don't know exactly why elliptic curves are good for cryptography, but I would hazard that the reason is perhaps only apparent when you study them in the abstract - hence why you don't see this explanation in your resources. The writer might not even know themselves.

[1] Yes yes, this is broken as well. In my ideal university there would be no semesters. Courses will be as short or as long as necessary to naturally end at an appropriate location.

> Nowadays technical problems are often solved by writing code, which is almost never done on a chalk board outside of job interviews.

Nope. They are solved by either formulating a solution in maths or drawings or verbally, then it’s transformed to code step by step. Code is just your intention or solution distilled for a much more constrained machine, and is the very last step.

Maybe in your field, but in over 40 years of work in a pretty wide variety of technical fields I have never seen a single person write an equation on a board as part of doing actual work.

Interesting, because I find myself writing formulae to my notebook all the time. It's not differential equations all the time, but I'm generally making sure that something is scaling correctly, or the things I'm doing are the ones I really want.

I would love to have a board at office, but instead I have tons of notebooks which I finish, scan, shred and recycle.

To positively add to your viewpoint, my experience as first a student and later a professor is that many students prefer slides/notes to blackboard because the former often gives them the perception that they learn more.

Slides/notes are fixed content. It's also finite content that you have to learn. If you learn all that content, you have mastered the course. So, it's quite easy to assess how much you have learned. But slides/notes don't teach skills well, and teach even more poorly on how to think in the course domain. Books also do poorly at this. The only way to learn skills and ways of thought is, as you say, by imitation. The imitation happens on the blackboard, where a good lecturer thinks out loud, gets the students to think out loud with him, and hopefully transfers the rhyme and rhythm of the discipline to them.

The 'problem' is that you can't really nail down concretely from a blackboard lecture what you are supposed to learn. Moreover, no matter how much you read the book, and master the content, you will always feel like you aren't thinking as well as the lecturer was. So you feel bad. Of course, if you let the pain drive you, you continue on your path of learning. If you don't, then blackboard courses feel horrible [1].

[1] A huge percentage, I would hazard, majority of lecturers are not of sufficiently good quality. Teaching is incredibly difficult. So, many blackboard courses, as do many notes/slides courses fail because the lecturer was just bad.

I guarantee 75% of your students got lost along the way at some point, and — having lost the train of reasoning — are simply waiting for the class to be over so they can review the textbook and try to make sense of the subject matter. At least for difficult classes like physics and mathematics, which require uninterrupted thought and reflection to achieve understanding.

Well it's silly to assume that these are mutually exclusive methods of teaching. As you well point out, prepared material on a computer can show things that you simply can't on a blackboard, things like visualisations, graphs, schematics, or other things that are either too tedious or impossible to write down on a blackboard and copy to a page.

My rule of thumb is: screen for exposition, blackboard for problem-solving.

Since there is no space inside my house, to put a decent sized blackboard and I don't have free access to one, maybe blackboards aren't so democratic as one would wish.

I have known people who lived in a run-down studio apartment or just a bedroom in a shared house who had a sizable blackboard or whiteboard. So this is clearly more of a personal choice about your space than anything inherent about the tool. But if you are by yourself or with 1–2 colleagues (not trying to explain to a group) you can certainly do the same work on paper. Reasoning through a problem on paper becomes unworkable when you try to show more than a few other people at a time, which is where the blackboard comes in.

I think a blackboard is cheaper than any device that lets you view PDFs

If you want to learn writing, wouldn't it be much better to see someone write in a word processor, to write with the same tools that you will also use?

No, a word processor is a very poor tool for reasoning through the solutions to technical problems, compared to paper or a blackboard. You need to be able to draw, doodle, make tables and charts, write with whatever symbols you can imagine, etc.

Once you have a solution in hand, you can use computer drawing tools to make a polished version for publication. But that's a different problem than the original reasoning.

What are you going on about? There is no ‘reasoning’ or ‘problem solving’ going on in real time. The professor is transcribing an already prepared lecture, oftentimes literally with the prepared notes in one hand and the chalk in the other. Real problem solving is a tedious, nonlinear exercise with many dead ends and start overs. There is nothing in a prepared lecture for a student to imitate.

I don’t understand the rationale behind assuming everything old is worse than today’s methods, technology.

I still get my pens and paper when I design a software or study something that I want to learn, and it works trillions times better than watching a video or going through some slides.

I still produce my notes & documentation from books or existing material, and retain that knowledge almost indefinitely.

There’s mounting evidence about both people have learning differences, and using pen and paper exercises the brain in a completely unique way.

Ignoring this is pretty counterintuitive from my perspective.

Blackboard and chalk are an artifact of a time when students came to classes prepared and could follow.

I did engineering at Cambridge and they had the best solution to this problem: fill in the gaps notes.

It might sound crazy but it has none of the downsides of no-notes or ready-made-notes.

* you have to pay attention and turn up otherwise you end up with useless notes, so it still has the motivation factor of no-notes

* you don't spend all your time copying so it doesn't suffer from the "I wrote it all down but I didn't listen to a word" factor of no-notes

Any examples ?

Not the best example but here's one:

https://www.studocu.com/en-gb/document/university-of-cambrid...

Bit difficult to find because they aren't publicly available.

Thing is, making you write what you hear improves meomory and info retention and retrieval.

PDFs Are a nice tool for the big books where you need lots of texts, images and diagrams. The scribbles are more for helping to remember past lectures.

But when everything is a PDF, knowledge becomes too fleeting to even remember past the exams.

Please don't speak for everyone.

I learn best from lectures by paying careful attention with my eyes and ears, and keeping the narrative flow structured in my brain; trying to write a substantial amount disrupts my focus and leads to dramatically worse understanding/retention.

Other people learn best from lectures by writing everything down (but never looking at it again); just the act of writing helps them focus. Still others learn best from writing without worrying about understanding the first time, and then afterward repeatedly reading their written notes.

(If I wanted to be e.g. an ethnographer or journalist, I would have to be the type to write notes after the conversation, rather than during.)

This, but I want to add that at least for my physics classes, blackboards add two sources of errors : the teachers mistranscribing their notes on the blackboard and me mistranscibing the notes from the blackboard. Especially bad when it's a bunch of formulas with greek letters and you can't tell the prof's alpha from a psy.

On top of me not being able to listen, my notes were basically useless

I think what may be the case is that blackboards are the best way to learn something you already loosely know. You can follow along and need to rapidly identify new information and compress that information down for your notes. But if you don't know it, yes, you will get lost and fall behind.

I don't agree either. I don't learn well in a classroom, I went through all of undergrad and grad school skipping every class and only depending on PDFs of lecture notes, PDFs of handouts and textbooks. Lectures, especially with blackboards were the absolute worst for me.

I know some people who just got through med school by reading, using Anki, and watching videos of past lectures at 2x speed. Lectures are a horrible way to learn and watching someone slowly write something down on a blackboard or whiteboard is a despicable use of a learner's time.

For collaborations, things are entirely different of course

My Calculus Professor liked blackboards because he could slow the down material for everyone.

He told me he started off with slides and stuff and thought it was going to be all slick and cool for everyone. Then he eventually realized it just goes through material too fast.

> Technology has not improved on the blackboard at all.

I think whiteboards are an improvement on blackboards.

Except for the fact that 99% of the time when you pick up a whiteboard marker it is dried out. Chalk doesn't do that.

And whiteboards eventually stop erasing well. There are some huge whiteboards at work that I’ve been trying to resuscitate but none of the remedies I’ve read about online work very well. Whiteboards seem to last 5-10 years, depending on usage.

Blackboards also stop working eventually. What the means is that repeated writing, erasing, occasionally using water to clean them completely, makes tiny little holes in the paint. Then when you write, the chalk gets into the holes and it doesn't erase well with a standard eraser. So you have to use more water, which causes more damage...

Blackboards in universities are often painted over with new paint after a few years. Of course, this is relatively simple maintenance.

I just really don't like chalk dust, others have a higher tolerance I think.

Only if that works for you, though.

For me to write stuff down in real time I basically have to turn off the understanding part of my brain and become a dumb pipe of sounds goes in ear to words on page.

I can hear and write, or I can listen and learn, not both.

I can’t both listen well and take (extensive) notes. I have to pick one. Listening in class tends to be better, because then I can ask questions and will have followed along with what’s going on at least once. If the topic’s at all tricky for me, I will gain almost no understanding if I focus on notes instead, and sure, I’ll have notes, but I’ll otherwise be starting from scratch. I will not have followed what they’re about, when taking them.

I think the article is more about professional mathematicians communicating among themselves, not teaching in a classroom.

Today we have the technology to do both: allow free-form drawing, while also recording a presentation and the scribbled content. You don't even need a fancy smart board, just an ipad projected works.

I taught this way during the last part of Covid for a few courses and it doesn't work well. I am forced to stand (sometimes sit) in a single location, for a long time while I am writing. Its much harder to motivate students and keep them engaged in such a static manner. You need to move around the class, see the class from different perspectives [1]. You are alive, the students are alive.

Also, you can't get students to come up to the board when using these fancy ipads and such. In my opinion, just video recording a blackboard lecture is the correct way to go.

[1] You often don't see confused students from one vantage point. Walking around, that you do naturally while using a black/whiteboard or even when using slides lets you do that.

Today we also have videotape. I wish all the lectures I attended had been taped. I'd like to retake those courses via the tape.

You remember something by putting some effort into working with it, and so writing down the content from blackboard is just such work.

It is a bit similar to reading a wide-format newspaper than reading text on your smart-phone. larger area lets you see more at the same time, you don't have to go back to previous page so often.

Reading an article on a phone is something I'd only do if I had no alternative and really wanted to read it.

Motivation is funny like that. I've struggled to work through a paper I didn't even want to understand but had to write an assignment about on an A4 eInk tabled or using the perfect note taking setup, but I've also read a full book and 10k+ words blogposts on my phone or filled in a PDF crossword by placing single-letter text boxes in preview on my mac.

Yes, reading something you are interested in and is readable, is easy.

As a kid I used to consume Enid Blyton books without really being aware I was reading them or how much I had read, I was just "inside" them. I wasn't trying to read them, I just did.

I was looking for the chalk v marker on whiteboard shootout, and it was conspicuous in absence.

Chalk is superior. You don't hear about anyone hoarding whiteboard markers. https://www.youtube.com/watch?v=PhNUjg9X4g8

I don't have to hear about people hoarding whiteboard markers, I see it all the time.

I have a blackboard in my home office. I was quite surprised to find that a lot of them are available on e-bay and that they are quite cheap: I think, what happens is that, when schools get rid of them, teachers will sometimes take one home for their kids. Then, when the kids grow out of it, the blackboard ends up on e-bay.

So, when I moved places, I used the opportunity that I already had a moving van rented and picked one up from someone selling one who was quite nearby, paying €50 for it.

When I opened it, I realized that it had chalky deposits all over it that didn't go away with normal cleaning products. So I had to use a brush-bit for a power drill to scrub it clean.

Then I found that I only have dry walls with hollow spaces beneath that can't carry the load (it weighs maybe around 100kg), so I made a technical drawing specifying a stand and went on etsy to look for a metal-worker who could make me that stand.

All-in-all, it was just laying in a corner in my office for about a year until I finally finished the project of setting it up.

So, it ended up being a lot more hassle than I thought it would be, but now I'm quite happy that I have it.

There is paint that can make whatever you are painting supposedly gets a blackboard surface. Not much help for you but maybe to the interest for others.

I always wanted to have a blackboard at home, but I’ve been convinced the chalk dust makes it prohibitive.

You couldnt fasten it to the studs in your wall?

I think this is when we know something is in the past: A nice tribute.

Recently I bought a paper notebook and pens to make companion to my ipad+pencil+OneNote combo, for my Rust programming studies and anotations.

Before buying the notebook I researched what kind of notebook Einstein used to work on. Spyral x brochure, kind of paper and size were considered.

Something was off with the digital solution. I can't ellaborate exactly what was/is the problem, but I'm not abandning it. I use it when it feels more up to the task (ex:storing images and coying a big text from the internet).

Everybody has a preferred learning style but I agree that presentation handouts (assuming the slides are well designed/done and with enough space) are a great way to highlight and add your notes and pay attention to the oral explanations and reasoning instead of furiously writing/scribbling and sometimes deciphering the hieroglyphs the prof wrote scratched on the green blackboard.

I've never really used a blackboard, but there's definitely something about physically writing on a surface that can be erased and rewritten at will. All electronic versions I've tried are a joke in comparison.

I think the blackboard specifically is just something Hollywood likes and perhaps a few people's preference. But whiteboards are better really.

I remember being punished as a child and having to erase the things, then "clean" the erasers by pounding them together . . . surely a recipe for silicosis! ;-)

The point is that cleaning the blackboard and the erasers wasn't "all you can eat cake." It was messy (hard one to explain to the parents!), sneezy drudgery.

chalk isn't a silicate. It's calcium carbonate. So no worries about silicosis. I think otherwise it would have been banned from schools long ago.

Reply on news.ycombinator.com