This is CS 50 Podcast.

My name is David Malin.

My name is Brian You, and it's been a while since our last episode, but that's only because Brian and I insist that this whole team have been rather busy here in Cambridge and in New Haven, teaching the fall version of CS 50 on campus at Harvard and Yale.

But we're back now, and we thought we'd begin the coming year.

But the discussion of how the past fall went indeed, the story really begins back in June of 2019 the start of summer here in Cambridge, when we gather the team together for so called Summer 50 a retreat where we all go away together for a few days to discuss the coming summer's projects, coming fall's changes and really the coming year's curriculum for CS 50 CS 50 x, CS 50 AP, and the theme that we decided to focus on back in June of this past year was a chapel auntie to move forward, to evolve the course, to change and make a really thoughtful reformulation of what it is we wanted to do and what it is we wanted to teach in the class.

And that led to a whole list of changes that we actually announced toward the talent of this past summer by a C s fifties medium Blawg titled A Job.

Volante is Well, it's kind of amazing looking through this list, just like how many changes there were that we were trying to put into effect this year.

Like it feels like the course definitely changes from year to year.

But this year, especially, it feels like there were a lot of new parts to the class and things that were just doing differently.

Yeah, absolutely.

This is probably in the 13 years that I, at least have been helming the class, probably the most significant overhaul of the curses, structure and curriculum on design.

Really?

So we thought we'd share some of the thinking behind what those changes were.

Us do a bit of debrief as to how we think things went and highlight not only the successes we think, but really some failures, things that we thought were a good idea in June of 2019 but didn't really pan out as we'd hoped.

So lectures for years have they been one of the defining characteristics of the course in so far as they're designed to introduce the week's concepts, particularly those concepts that students need for application on the courses, problem sets or programming assignments.

And in recent years, it's worth noting that attendance here in Cambridge in person on campus really has been declining.

And this is not in and of itself problematic.

And indeed, we, the class and I philosophically have very much been in favor of what we call here on campus.

Simultaneous enrollment, the ability for students to enroll not only in CS 50 but maybe even in some other class on campus that meets at the same or overlapping time, the implication of which is that they have to physically choose to goto one class or the other.

Insofar, Osias fifties materials have long been filmed, and we placed such emphasis on the quality of the digital materials we have been comfortable in telling students go to the other class and watch CS 50 in person.

However, this is, of course, had the side effect quite causally off.

Relatively few students attending the courses lectures in person, even after just a few weeks of the class case in point, I think in fall 2018 we had maybe 152 100 students out of nearly 800 physically attending by only the third or so week of class.

And I don't think that's really specific to CS 50.

Like I feel like all across Harvard and probably universities more generator like If there's a way for students to watch lecture from the comfort of their home without showing up, there's gonna be much fewer people that actually end up showing up to the lectures.

Yeah, that's quite fair.

Certainly, in computer science and other fields here on campus, there's a long standing tradition of filming classes and that it certainly has value.

And so far, students can review material.

If they miss material, they can catch up.

But indeed, I do think we see students walking literally with their feet out elsewhere.

Well, I'm curious.

When you were in college, were any of your classes filmed and did you go to class or were you more of the watch?

The video?

Oh, I was super uptight and always the one going to class.

I don't know if I ever missed.

I can think of a class who's sections I missed.

I'll admit that I realized halfway during the term that an economics class I was taking actually had sections which somehow I forgot about.

But I want all of my CS lectures and sections, and at the time, if you missed a class back in, what 1995 to 1999 you could go to the library for some classes and asked to borrow the VHS tape, which you then watch on a machine there.

Although I did take a networking class at Harvard, I think in probably 1997 taught by Professor HT Keung, who's still in the faculty here in computer science.

And he was, to my knowledge, the first professor to stream his courses lectures online.

So it wasn't live streaming, but it used is a technology Microsoft Net show, I think.

Itwas so.

This is well before we had the sort of YouTube and empty fours and all streaming technologies of today, and we actually in a tiny window that was probably like 100 and 60 pixels wide, were able to watch lectures from home if we wanted.

We made a lot of progress and screaming now, but in any case.

This is something that we have been encouraging or certainly allowing and endorsing.

But I do feel in recent years and certainly last year when we saw these numbers, that too many students, I think we're sort of following in the footsteps of their classmates without necessarily making an informed decision themselves as to what would be best for them to learn the material.

I think too many first year's freshmen who had just arrived on campus, who had spent the past four years presumably in high school, going to classes and now we're suddenly stopping because they saw more upperclassmen doing the same was probably not the ideal informed decision, and ultimately it was just having a ripple effect, I dare say, like CS 50 has such an operation behind it in terms of so many teaching fellows and so many sections and so many office hours that if a student does not go to a lecture and then for whatever reason, ends up not watching the lecture live or on demand later on in the evening or even the next day, it means they show up at our on campus sections, led by the teaching fellows unprepared for that section, and then they dive into the problem set and they're unprepared for the courses material.

And then they come to office hours and then ask us questions for which they should have been prepared had they been prepared for section and prior to that in person in lecture.

So it really had an operational cost, I dare say, which then cost other students.

Ah, in so far as we had fewer resource is to answer their questions.

Yeah, and I really noticed that I think that really improved this year.

It felt like in section in office hours, like students came to them prepared, having been to lecture, whereas normally a lot of students would wait until later in the weekly cycle in orderto actually watch the lecture and begin to engage with the materials.

That was just more time to be able to think about things, to take the pace of the problems.

That's a little more comfortably just to make the week a little more manageable.

I'm really going to hear that because that, of course, was our hope that we would actually have this ripple effect in a positive way.

On subsequent support structures and oh my God, it's so liberating as a teacher to be able to say something or repeat something for a student and be able to assume that they were there the first time.

So you can draw contextual references and put things that the context where is in years past there was maybe a 25% chance that a student in talking with them had been to the most recent lecture.

So I dare say this change that we rolled out, which was, quite simply, to effectively require attendance at lecture.

Ah, the course had some nine lectures in total in person.

This year, an expectation was that students attend at least the 1st 8 of those which is not all that unreasonable.

There a couple of hours a week, it's only eight lectures, and so that felt like a reasonable compromise, even though philosophically, I dare say rarely and more libertarian, and that students should be free to do what they want.

But I do think it was a net positive to try to help students help themselves by effectively requiring attendance.

But even that keeping track of who was that attendance was non trivial.

O you were instrumental in solving that.

Yeah, we spent weeks trying to figure out, like, how do you take attendance for a class this big?

Like a lot of other classes, you can do that like, just call off all the names and mark check marks.

But that's not gonna work in a class with 800 students.

So we had to go through a lot of different possible options.

All the students here have I d cards and you can think about different ways of trying toe swiped them or try to scan them.

But even swiping them is gonna take a long time.

If you only have one swipe for, like, 800 different people, all of whom arrive in the five minutes before class is supposed to begin of, right?

Exactly.

And you wanna make sure that doesn't have a huge bottleneck in a long line.

So we eventually settled on a system where we have these, like four scanners, the type of scanners that you might see like at a grocery store checkout when they're scanning the barcodes on various items with laser scanner is getting the barcodes on the I D cards on.

We had four of them a different entrances to the lecture hall on that tended to work pretty well.

I think they're a couple of lines that built up right as lecture is starting, but generally it worked pretty quickly and we were able to get people inside.

Well, I'm so glad it worked out because it's a slippery slope.

We had talked about writing our own custom software and how you go about attaching some kind of scanner to a tiny device, whether it's an iPod or an iPhone or maybe a raspberry pi.

And they're just felt like it would be fraught with technical support challenges if something went wrong.

You're sort of dead in the water, but these things, they're pretty dummy proof.

They're meant to be used.

Ah, we saw for, like, warehousing applications, someone going up and down an aisle, presumably taking inventory.

Yeah, I think that was that's intended use case, and it works pretty well when you're trying to scan a lot of things very quickly.

So for our use case, I think it's pretty good choice.

Yeah, and so to incentivize students to come because it's not a road requirement that you come to lecture but it's an expectation we actually did for the first time.

Really, though we saw some prior incarnations of this idea on experimental form in past years, um essentially had a participation portion of students grade where you get it all if you meet all expectations coming to section, coming to lectures as well.

But it's amazing.

It's amazing to me that not only asking students to come to lecture but incentivizing it as with some fairly small numbers of points toward one's final grade, it worked wonders.

We went from like 200 somewhat students to 650 consistently week after week.

I was amazed every time you guys took attendance or reported back after the scanners were done, it being used like it was around 6 50 every week.

So doesn't feel any different when you're lecturing in front of 600 people of the post to a much smaller big time, feel more pressure when they're that many people.

Oh yeah, no, I We have photographic evidence.

I sweat every lecture this year.

Where is in the past?

I actually wonder.

I used to blame the temperature in Cambridge and the lack of strong air conditioning in the building, but I think it's my nerves, my heart rate.

And I should probably check my apple watches history of my heart rate during that 3 to 5 PM slot on Mondays.

Um, to see if that partly explains, but yeah, no, I was much more nervous.

You know as well as anyone that how much more I and we prepared before each lecture because you just have so many more eyes on you.

Uh, and it was good pressure in a way.

And the energy is just so much better.

We had many more volunteers.

There was more audience participation, both in terms of questions and answers.

And when you have the occasional applause or laughter, it's sort of infectious and a good way, and it actually does motivate, I think, the experience of coming to a lecture So we didn't want people there just for the sake of being there.

We wanted them have a hopefully an inspiring or at least an eye opening experience, and I think you can pull that off like eight times a semester.

I I would not want us to do what we did some 13 years ago and have three lectures a week so that we now have some 30 classes that students have to attend in person.

Beyond the sort of up front cost of setting up for and striking our TV set up for each of those lectures.

I just don't think you need 30 times together to sort of feel that shared community experience, like eight or thereabouts feels reasonable.

Yeah, I think so.

And I student.

It's nice because you didn't get Tau get to know each other based on the people that are sitting next to, and they can have conversations about the material, which you just can't do as well.

If you just at your desk alone watching the electricity Well, especially for first years, theoretically, maybe even rub shoulders with more people that you meet and then stay in touch with more than you would if you were just in the library or at home watching on your laptop.

Now we should concede that we also changed the day of lectures this past year.

Past couple of years we've been using Fridays, or at least last year we did, and it was Friday mornings of all things I think was 99 a M officially to 11 45 that we typically started a little later closer to 9 45 so that we still had a two hour window.

And we know statistically from CS 50 Zone Data and Harvard College.

His own data Friday is hands down the least popular day for classes, both among students and reportedly among faculty.

It's hard enough to get students awake in the morning, let alone Friday mornings.

I'd let alone David and the team, but but we steered toward Friday because of exactly this.

It was wide open on Sanders Theater schedule, which meant we had the ability to book the room the entire day, which is great for CS Refuse Production Team because they Scott Dr 6 a.m. for a 9 a.m. or 9:45 a.m. Class just to set up the A vehicle.

It mint in technology and test everything, so there's a huge amount of set up, So just having that runway was liberating.

Plus, theoretically and tragically, it didn't work out this way.

You'd think more students would be free on Friday mornings.

9 a.m. because statistically they don't have conflicts or other classes and there probably aren't extracurriculars going on at that hour, but there is a lot of sleeping or non attending going on at that hour to Yeah, a lot of Steven's just tried to, like Free up your Friday like it was a goal among many of my friends senior year to, like try and arrange your schedule So you didn't have to go anywhere on Friday, and people tried to get the view, but, yeah, they were very successful at that inn.

Follow 2018.

So in short, I think this was a net positive, I dare say.

I think the lectures and hopefully the audience, is the students.

Engagement with them was so much more positive, an experiential this year than in past years.

Hopefully, we really did set students up for more success each week in so far as they now had gone to a lecture and therefore went to section prepared and then went to office hours or didn't go to office hours because they didn't necessarily have a CZ many questions and ultimately succeeded.

The problem sets because they had all of those building blocks ready, ready for them and without jumping ahead too much.

I think it's I would like to think, although there's many other factors that we should discuss some day CSF.