And here are the results, which you should now see on your screen, particularly down toward the bottom for all of the courses.

So what office hours are at harbor?

There an opportunity for students to drop by professors offices for an hour and just talk about the class?

Talk about how life is going, any questions they might have about academics in the real world.

So even though we're all in just a virtual office today, the goal is just to interact and chat a bit about topics enter on your minds.

Let Brian and I just asked that if you have questions that are specific to a problem set or a project like code, let's answer those on slack or on discord or on Ed or some other tool, because I don't think we could do a very goodjob debugging.

People's code live on video here today, so let's focus more on concept without further ado.

Why don't we go ahead and start the questions and answers?

I see galaxy M 20.

Your hand is up first you want to go ahead and amuse yourself and ask a question of the group.

Galaxy M 20 Still muted Galaxy M 20 No.

All right, let's move all round.

Will come back to you, if that's OK.

Tony?

Sue, is it?

Can we start with you?

Yes, Yes, this is Tony.

I'm Tony Sue and right on from Taipei.

I actually have a couple of questions I've have to want to ask.

But right now, the most pressing question I'm curious about is really mostly about security.

I really only programmed for one year.

I sometimes stream my coding sessions online.

And like some some of my developer friends and coffee shops tell me, Don't stream your coat on.

Nine was like Everyone sees her secret key.

Everyone sees everything.

Andi, I'm just wondering what one of the typical conventions to two to basic security management for for during development or doing a post development for managing APS.

Our What should I even do to find you get nto network security, cyber security or with python?

Or like if I have some analytic skills with five phone and so on and so forth?

What should I study and stuff like sure.

Why don't I answer the first part and in turn, in the latter part over to Brian.

So if you are live streaming your code and with it your secret keys on the Internet, don't that is bad like that?

You answered the question yourself already.

If you recall if you'd taken CS 50 your CS 50 Web, you might recall that any time we dealt with secrets like a P I keys, we would encourage you to put them into what are called environment variables, which put them into the computer's memory.

But in a place where it's not in your code, which means people on the Internet can't see it if you're live screaming and you don't accidentally therefore push it to get hub or save it in your code repositories if you're using version control.

So generally speaking, anything you put in your code really shouldn't be that sensitive.

You should not have passwords, not secret keys or the like.

Use some other mechanism for those as for python itself in security practices and learning Maur Brian, you want to take it from there?

Yeah, I mean staring.

If you're interested in learning more about security that the domain had suggest looking into is the whole world of cryptography, which is this very sort of vast discipline within computer science.

All about trying Thio communicate things securely, which is becoming very, very necessary in the context of the Internet, where you want to be able to send messages to someone across the Internet.

You want to do so securely so that nobody in the middle is going to be able to access whatever information you're trying to send him.

And there are a whole bunch of now algorithms and libraries that exist in languages like Python that might be worth exploring there.

And this is this kind of cryptography is the basis for how communication over the Internet works.

It's the basis for how crypto currencies like Bitcoin work if you're familiar with preferred of bows.

And so a lot of applications now of these cryptographic techniques and we talk about these a little bit and see a 50 the Web programming class, but definitely a lot more there to explore.

Wonderful Well, thank you for that question.

Can we go next to let's say, uh, more Moritz, if I'm saying it correctly, Uh, yes, Hello.

Um, my question is, ah two parter.

So, um, I started out programming with CS 50 X and, well, our university semester is kind of on hold now because of the whole Corona virus situation.

And I've long considered the CS 50 ex in particular to be the master class when it comes to like a teaching programming with in an online kind of environment.

And I'm sure that a lot of work has gone into getting it up to that level.

And I'd like you to share with us some of the insights that you had going through developing this like online course and all of the material and what perhaps other educators could take away from it to improve their own materials.

Well, thank you.

First of all, I can say that it's been very incremental over the years what we've done with CS 50 and I think what you see now is really the aggregate effect of a lot of efforts by myself by people like Brian by other members of our team over the past 13 years now since I took over the class and I think the simplest answer from the get go is that we set out some time ago, really, just to solve a problem.

So back in 2004 or so, I was teaching a different class at Harvard's Extension School, which is our continuing education program for adults, primarily both on campus and off, and that the time heartburn was using video technology called real video, if any of you remember it, it was one of the earliest streaming video formats.

It wasn't that great, but it was still cutting edge nonetheless at the time.

But it didn't allow you to save the videos locally.

It didn't allow you to take the videos with you.

And so it was around 2000 for that.

I think the first iPod came out, give or take, and podcasting became a term.

I didn't really know what.

It was interesting to us that we could allow our students in that class to maybe download these videos or even MP three's audio recordings of them, and then take them with them on the train.

What toe work to the gym on the treadmill.

And so we really started doing everything on the Internet just for our own students.

Take.

But I did a whole lot of people around the world start tuning in, which was a pleasant surprise to us.

And then in the years since then, did we very consciously start making sure that any materials we creates are digitally accessible as well.

And this is P.

D efs and this is handouts, and it's a software and everything else, and we also became more sensitized to internationalization.

So very early on, we would ask questions about American sports or even U.

S currency, which, of course, if you're living abroad like many of you are you might not have those same experiences or backgrounds.

And so I think in recent years to we've tried to be more culturally sensitive and geographically sensitive to students disparate backgrounds and not assume anything.

And so now we still have a problem set you might recall on cash a greedy algorithm, but we define for everyone what a nickel is, what a dime is and so forth.

And then lastly, I think I would propose that it's thanks to members of our team, one of whom is cut fuel from actually are on this video call with us today in and are thorough and Ramon we have this amazing team focusing on videography, and we now scream in widescreen four K video.

And I mean, that's very deliberate, too.

I think all of us take pride in what we're doing.

And the goal is not to have, ironically today small little video streams of people normally but media that really draw the students in and make education as engaging, if not entertaining, as possible.

I mean, I spent 18 plus years in high school and and prior, not really loving school.

I sort of worked hard just because I thought I should.

But I don't think school needs to be this obligatory thing.

I think it can be a passion.

And so we've tried to create, We hope, an environment that draws folks like yourself in Thank you for asking.

Can we go to the next question here?

How about from looking for some blue hands?

Uh, Debashish, if I'm pronouncing that rights against the green screen still muted?

Yes.

Okay, so I was asking for you.

You're brilliant from your boob.

Hello?

Yes, we can hear, um, a lawyer from your true I want to know.

Uh, is there any more pictures you polo from Elect a few fulcrum.

Uh, hello?

Um, yeah.

Can you say that the question again.

Can you suggest a more videos?

But we can get up from the Internet like I'm from India.

And I follow your your toe Berrios and see if the collectors Hello?

Yes, we can hear you.

Okay, I know you're seeing live just on Get Jennifer just some more.

Uh, you're a collector for some left from Internet.

You, Carlos, we did a comment.

Yeah.

Let me let Brian answer this to There aren't that many courses I've taken online.

To be honest, I tend to be so focused on what it is we're doing with some bias.

Let me paste into the chat window, which you should be able to see.

This, of course, is all of CS fifties courses which go beyond CS 50 itself.

Brian now teaches a course on Web programming on soon on artificial intelligence.

But another one that I do like, let me go ahead and google it real quickly and then paste this as well.

Eyes, of course, from Princeton University on algorithms, it's freely available on course era.

And if you're looking to learn a little more or C s theory.

See the algorithms class that I just pasted into the chat window as well?

Brian, I think, is a better student than I am.

Do you have courses you'd recommend?

Thio?

Other courses I recommend really depends a lot on your interests.

Eso if algorithm to something that are interesting to you.

Definitely.

That course or a class on algorithms is great.

Um, a former Harvard professor, Jelani Nelson, taught in advanced algorithms class at Harvard to and most of those lectures are also available on YouTube.

If algorithm designed is something you're also interested in on depending on your other interests.

M i t has a great class on deep learning.

If machine learning is something that you're interested in, they have a great course on deep learning that's available on YouTube is well on.

Then I personally and I studied linguistics and college and very interested in natural language processing.

Stanford has a great online class about natural language processing, too.

Eso lots of universities make a lot of their courses available online.

So just a little bit of looking around, and you can probably find the ones that I just mentioned and also a number of others, too.

Indeed, police feel free to paste your girls, Of course, is into the chat window.

For everyone is, Well, let's move on.

And if you do have your hand up.

But your video is not on if you do have a camera to try to turn it on, because it'll make it easier for us to to see you literally on interact about.

Next question from Sue House.

I'm saying it right.

Hello.

So I have I'm doing CS 50 x 2020 and I have a friend who did the 2019 goes and based on what I taught them, my personal.

I don't know if this is too, but I felt as if the 2019 1 was actually tougher than 2021.

How do you decide, like the the pieces off each year?

Like someone you change some of the material.

So how do you decide which ones to keep and which ones to replace?

Yeah, it's a really good question, and Brian and I especially spent a lot of time last summer summer of 2019 thinking about what problem sets to change which ones to keep their several that we really like.

So, for instance, Mario, which, of course, is the 1st 1 cash and credit we've used for many years now CSFB finance on the end of the course we've used for many years now, But there's always some number of problem sets that I and Brian and the teaching fellows don't quite love, either, because it's not quite as engaging as we would hope, or it's not quite focused as we would like on some subject.

So Brian wonderfully came up with a long list of new problems.

Said Ideas.

I after 13 12 years at the time, was running low on new ideas, and he wonderfully infused us with a number of new problem sets.

And in fact, do you, Brian, want to speak to what guided your decision making there?

Yeah, sure.

So a big part of the guiding idea is that we have We were coming up with new problems for CSFB.

X 2020 was thinking about the different backgrounds that people come to this class with that most of people that are taking the cost.

They haven't had computer science doctor on before, but they may be come with some other background that maybe they know a little bit about government or maybe know a little bit about biology from other classes they might have taken.

So with a lot of the problem sense that we've created, especially in the past year, we've tried to integrate computer science with other fields and try and show how you can take the skills you learned in CIA 50 and really apply them to other domains outside of computer science.

And so if you've done the CS 50 X 2020 problems, you might be familiar with the election problems there.

Three different election problems that are all based around the idea of trying to simulate an election.

And various different election algorithms on these algorithms come in varying, different degrees of complexity, which lends itself really nicely to our less comfortable and more comfortable problems, where we like to offer a bit of a more comfortable challenge for students who would like to try a more challenging problem or complete one of the problems and are looking for another problem to try to complete this Well, eh, So we created a problem set to integrate with government.

We created a problem set to integrate with English and literature in the context of the readability analysis and problems that tomb on.

Then we had another new problem.

That was all about biology in DNA analysis in terms of the types of things that happened in criminal justice investigations.

And so problems at six now includes that as well.

And with all those problems, our goal was to try and create something interesting to really demonstrate the power you get with just a couple of weeks of learning about programming and learning about computer science.

And so, just to get a sense of what country are you from?