February 29, 2024 • 31 mins
What have Braille and Burger Emojis got in common? I take a deep dive into the subject of Data Representation with the help of my special guest Andrew Virnuls of advanced-ict.info, we demystify binary, bit depth and sample rate, talk about cross-stitching, and I reveal the winners of recent competitions!
Transcript at httcs.online/blog. If you enjoyed this episode, buy me a coffee at ko-fi.com/mraharrisoncs or buy my books at httcs.online/books. Thanks!
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Episode Transcript
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(00:10):
Welcome to how to teachcomputer science, the podcast.
This is episode three.
and we'll start with a fertile question.
What have Braylin burgeremojis got in common.
I'll be answering that questionand many more with the help
of today's special guest.
One of my old lecturers askedme what I thought for me
epitomizes computer science.
And at the time I said algorithmsthen went home and I thought about
(00:30):
it, actually I thought no, it'sdata representation isn't it?
Because it links everything together.
More on that at the moment.
My name is Alan Harrison, and I wrotethe books how to teach computer science
and how to learn computer scienceavailable in online bookstores, more
details at the companion website.
HTTCS dot online.
That's the initials of how toteach computer science.online.
(00:54):
If you like this content,please subscribe.
Tell your friends, buy my books.
Leave a review or buy me a coffee.
details at HTTCS dot online.
Every week, I'll transcribethis recording and blog it at
HTTCS to online slash blogs.
So, if you don't like my voice let'sbegin to answer our fertile question.
(01:19):
What have Braille andburger emojis got in common?
Let's start our story over in Paris,
not far from where Disneyland Paris nowstands, in the town of Coupvray, in the
leather workshop of La Famille Braille.
(01:43):
Louis Braille injured an eye inhis father's leather workshop
at the age of three, and theresulting infection caused him
to go blind in both eyes by five.
At age 10, he obtained a scholarship tothe Paris Institute for Blind Children.
which at the time used asystem of raised letters.
Braille found the system hard to learnand when he was shown a system of raised
dots used by the military to communicateat night, he took it and improved upon
(02:06):
it using just six dots to representall the letters of the alphabet, plus
numbers and some punctuation symbols.
Each dot is raised or flat and ablank space, effectively six flat
dots separates words and sentences.
In this way, the grid of six dotscould represent two to the power
of six or 64 different characters.
Braille is therefore a binarycode for representing text.
(02:27):
If we ordered the dots as Braille did fromone at the top left, finishing with six at
the lower right, then each of the Braillecodes can just as easily be written
out as a sequence of bumps and flats.
So A is bump, flat,flat, flat, flat, flat.
And H is flat, bump,bump, bump, flat, flat.
Replacing bump with one and flat withzero we can write A as 100000, and H
(02:50):
as 011100, We can now write any textusing just two digits, zero and one.
Braille has created a binary codeto represent text, and electronic
computers have not yet been invented.
Fast forward to 1961, when IBM engineerBob Bemer proposed a single code for
computer communication and two yearslater announced the American Standard
(03:12):
Code for Information Interchange or ASCII.
ASCII is a lookup table thattranslates letters and punctuation
marks to numeric codes.
A character set thus enables thestorage and processing of text by a
digital computer, which also meansdata created on one computer can
be processed by another computer.
Originally a 7 bit code representingonly 128 unique symbols, international
(03:36):
popularity demanded more characters.
Various 8 bit versions, oftencalled extended ASCII, were popular
in the 1970s and 1980s, with an8 bit standard emerging in 1987.
Computer makers standardized on 8 bitbytes in the early 1970s, so the extended
ASCII character set made perfect sense.
But the 256 different bit patternsavailable from 8 bits were not
(03:57):
enough for languages such as arabic,
مرحبا
السلام عليكم
Chinese
and Japanese.
Konnichiwa.
and the Unicode standardwas inaugurated in 1991.
Originally a 16 bit code givingover 65 000 characters, a later
version called UTF 8 allows up to32 bits per character, which has
given room for all modern languages.
(04:18):
Unicode opened up the internetto non English speaking peoples
who had previously been forcedto work in European languages.
And in that sense, the UniversalCharacter Set was an important leveller.
As Unicode consortium lawyer AndyUpdegrove put it in a 2015 interview,
(04:43):
so why does all that linkbraille and burger emojis?
Well in each case real world informationhas been encoded into binary.
Braille is a 6 bit binary code, and emojisare part of the Unicode 32 bit standard.
This is all part of the computerscience topic of data representation.
At the heart of this topic isthe idea that if we can turn
information into binary data, wecan use a computer to process it.
(05:08):
Digital computers processbinary numbers because they use
two state electrical signals.
The challenge is therefore tofind a transformation from real
world information to binary.
This transformation is calledencoding, and it makes use of a code.
ASCII and Unicode are used to encode text.
JPEG, GIF, and PNG do the samefor bitmap images, and WAV, MP3,
(05:28):
and AAC encode digital sound
Ding!
as predicted by a brilliantyoung mathematician, more
than a hundred years ago.
(05:58):
But it's important to realize thatthere are virtually limitless ways of
encoding information, and these arejust the techniques that are widely
used owing to their effectiveness,or official recognition, or both.
That's really the fundamentalsof data representation covered.
The most important concept is weneed a way of encoding information
as binary, and then we've cracked it.
(06:18):
You can read more about datarepresentation in my book,
How to Teach Computer Science.
I am delighted to say it's notjust me rambling on today because I
have a special guest in the studiotoday hello to the man behind
advanced-ict.Info welcome, Andrew Virnuls.
(06:39):
How are you, sir?
Very well, thank you.
Good to have you on the podcast.
So you were listening to allthat, was that a reasonable
intro to data representation?
It was, and it made me think thatthat idea of the combinations is also
an important idea, isn't it, acrosscomputer science from things like,
how many rows you got in your truthtable, to the width of your data bus,
(07:01):
to colour depth, and in fact the waythat you can actually make a binary
counter using nested loops as well.
Yeah, absolutely.
Can you just tell us where you work andwhat you do, Andrew, for the listeners?
So, I am lead teacher and computingspecialist for a service in Warwickshire,
local authority service for childrenout of school for medical reasons.
(07:22):
So, effectively like a hospitalschool, but Warwickshire
hasn't really got a hospital.
it's interesting.
It's got some challenges.
So we get students from schoolsall over the county with a variety
of, , backgrounds and prior learning,and all doing different courses,
possibly, and some having learneddifferent programming languages.
(07:42):
That sounds really fascinating.
I mean, There's a lot of teacherslistening, thinking, well, I've got quite
a diverse bunch of classes in my schooland then, and then there's you with
well, yeah, in the same class a coupleyears ago, I had students doing three
different boards in computer science,most of them doing Python, but one
of them doing visual Basic, whichmade demonstrations of programming
(08:04):
techniques quite interesting.
Luckily, the theory is quite similar,actually, between the GCSEs these days.
Yeah, no, that's true.
And you've got a website.
Let me get the address.
Right, advanced-ict.Info, otherwiseknown as computing and ICT in a nutshell.
That's you, isn't it?
That's right.
It used to be called ICT in a nutshellbecause I created it back in the ICT days.
(08:25):
And it started off with the databasessection because I used to find every
year the A level ICT students would askme the same questions about, you know,
normalizing their access databases.
But I've added the computingstuff over the years.
I did, I did toy with the idea of.
Changing the domain name but I thought,well, actually, you know, I think like BMW
still use the propeller, even though theydon't make aeroplanes anymore, don't they?
(08:47):
Oh, that's a good
point.
Yeah.
No, I have used, I've usedyour website in the classroom.
A number of times, there's somereally useful stuff on there.
I like the bitmap generator thingto demonstrate things like bit depth
and number of colors relationship.
And, and we were talking about thesound wave one recently, and you've
improved it after conversations with me.
(09:09):
I think sampling the sine waveI think that's really useful.
There's some great stuff on there.
So
the metadata one was the interestingone because we were talking about
misconceptions and I suppose it'snot quite a misconception, but I
found that the students didn't reallyremember what metadata was for.
So I added that you could uploada picture and basically it shows
the pixels but just arranged intoa square, so you have to kind of
(09:32):
rearrange them into the right widthand height to reconstruct the picture.
So knowing the colors of the pixelsisn't enough to reconstruct the picture.
You need to know howthey're arranged as well.
Yeah,
I like it.
I like it.
made a note that I wanted totalk about today the parallels
across different file types.
You know how things like bit depthis the same principle in JPEG
(09:56):
images as it is in digital audio.
So the number of bits in a sampleis the same concept, no matter
what sort of file you're in.
Yeah, so yeah, the other thing I thinkabout image representation is there's
obviously different types of things.
One of the things I'm never sure aboutwith GCSE, for example, is what we do
(10:18):
about palette based file formats like GIF,because it was an interesting question
a few years ago, and it was one of thosetrue or false tables, and one of the
statements was the color for the pixelis stored in metadata, and I thought,
oh what if the actual colours are in thepalette, which is presumably the metadata?
Yeah, that's a statement that couldeasily be misinterpreted, couldn't it?
(10:41):
And I think I've seen questions likethat, exam questions asking where the the
colors are stored, and I guess there'sa difference between the color of a
pixel and the colors in the palette.
So I guess the palette needs to be storedsomewhere, and that would be in metadata.
Yeah so all of this stuff, so.
WAVs or JPEGs or PNGs.
(11:03):
Underneath, it's justbinary noughts and ones.
So somewhere in data representation,when you're teaching it,
you have to teach binary.
So how, big question,how do you teach binary?
Well, what I tend to do is first of all,say everything's stored as a number and
then say the numbers are stored as binary.
And I don't know whether I'mgetting better at explaining binary.
(11:27):
or just whether students have moreexposure to it but find as time goes
on they seem to struggle less withit because if you look on my website
there's a number base abacus which Iused to use quite regularly and I say
well you know this is it with tens andhundreds and things and you would Slide
the beads across to represent certainnumbers then say what would happen if
you only had one bead on each row andcould we make a number that way and then
(11:50):
say well basically you take that abacusyou turn it on its side and those are
your columns and you know those are thesame as the binary digits but actually
I tend to find I don't need to do thatnow I can jump straight to the noughts
and ones and they they seem to get it.
That's interesting I mean I guessour colleagues down in primary are
teaching this now, so it's it's goodto know that it's coming through.
(12:11):
I like what you said about the abacus andif an abacus only had sort of one bead,
I always try to explain binary as justa place value number system in the same
way that denary or decimal is and I'm atgreat pains to go back and forth between
decimal and binary and to reinforce thenotion of place value because it's just
(12:32):
a different number base, but the numberswork exactly the same way as decimal.
So I go over that placevalue thing over and over
again.
I think that's very important to sayand in fact I start off by saying
actually if you want to communicatea number, say four, what's all the
different ways we could write that down?
We could write it in roman numerals ortally and binary is just a different
way of writing it down effectively.
(12:54):
But actually the first slide of thepresentation that I use, because I know
PowerPoint's a bit out of fashion, Iteach mainly online, I don't know if
the listeners know that, so we haveto have something that they can see.
Trust me, PowerPoint is not going anytimesoon, but I know exactly what you mean.
I teach a lot less on PowerPoints now,but yeah, sometimes you need them.
Sorry,
(13:14):
carry on.
So my first slide is literally justa reminder of how denary works,
because I think that when you usesomething so often, you tend to
stop thinking about how it works.
So I'll show them why it's basedon tens, and the fact, you know,
as you move across, the placevalue increases by a factor of 10.
And in each position, you canhave one of 10 possible digits.
(13:35):
And then I repeat that slide when we lookat binary, and I use the same slide, I
just replace the word ten with two andthen replace the word two with 16, but
and then I also show them other things.
So in the same way that99 is one less than 100.
So effectively the largest valueyou can have in a given number
of digits is one less than thefirst unused column in that 111.
(13:58):
You could say, well, that's four plustwo plus one, or it's one less than
eight, which is the first empty column.
And then also the shifting idea.
So if you move numbersone place to the left.
They get 10 times bigger, if youdo it with binary, they double.
So it's about making it appear consistent.
I think that's the,that's the thing for me.
So I said in my intro to the podcast thatif we can turn information into binary
(14:21):
data, we can use a computer to process it.
And I called that encoding.
So we just need a different encodingmethod for different types of data.
So ASCII and Unicode are a way of encodingtext, how do you go about teaching
ASCII and Unicode in the classroom?
Well, I just, start off with everythingthat needs to be stored as a number.
(14:42):
So how do you think wecan, how can we store text?
And actually.
That's probably the most straightforwardof all of them in terms of the
students being able to understand.
So I just show them anASCII table and say, look,
everything's got its own number.
Sometimes they struggle with the idea thatuppercase letters and lowercase letters
are different, but I point out that that'sactually why, if you write in your Python
(15:05):
program and you say, you know, do you wantto continue y or n and they put a capital
Y, that's why it doesn't recognize it.
Whereas Google doesn't care orAccess or Excel tend not to care
in their searches because actuallyit's checking the aSCII values.
And similarly, when you sort thingsinto order obviously letters are, in
alphabetical order, but also things likepunctuation marks and stuff get sorted
(15:29):
into that order as well, presumablybased on the ASCII value of, those
symbols.
Yeah, no, that's a good point, and Ihadn't really thought of mentioning
things like sorting in algorithmsat this point when teaching ASCII,
but it's a good link to make.
So if we can get things intonumbers, we can process them.
So, Images.
(15:51):
Thinking of JPEG and so on, this isone of my favourite topics to teach.
Do you get the graph paper gridsout and get them to colour in?
Do you do colouring in whenyou're teaching images, Andrew?
I don't because I don't physically seea lot of our students, but I have, there
is a, there is a page on my website wherethey can click and color in the dots.
(16:11):
And I do explain that like,like knitting patterns as well.
You can kind of knit things withdifferent color stitches or cross
stitch that might be familiar with.
Yeah,
So there's a story in the book.
Did I mention I wrote a book?
There's a story in the book aboutthe woman who created the first
(16:31):
icons for the Apple Macintosh,and she was a cross stitcher.
Susan Kare, and she was hired tocreate some striking fonts and
icons for the Apple Macintosh.
So it's her fault you've got thebomb emoji and things on a, on a Mac.
But she was a cross stitcher and so itwas exactly the same principle of creating
images with just a grid of pixels.
(16:55):
It's interesting that idea as well.
You know, people say, whydo you need to know this?
But I think it kind of demystifies theprocess of editing images and things.
And that's why I created the page onmy website where you can upload a photo
and it pulls out the numbers of, youknow, the amount of red, green, and
blue, and you can add or subtract fromthose numbers and see the impact on
the image, and then you realize, like,Photoshop's really just arithmetic.
(17:17):
But then once you start thinking about howthings are stored, so one of the things
I say to the students is basically, ButComputers only deal with numbers so if you
want to store a new type of informationyou need to think about how you can
measure and store that as a number andI used to give the example of smell for
example so you know something unfamiliaryou need to think about how you do that
and then about two or three weeks agomy wife was reading the news one evening
(17:39):
and she said oh Apparently there's thisnew screen where you can lick it and
you can taste what's being displayedand my first thought was obviously
but I hope it's a personal device.
But secondly was, I thought,well, how does that work?
I said, could you,could you make a flavor?
By mixing together amounts of,you know, saltiness and sourness
and bitterness and umami.
(17:59):
And she went, yes, that'sexactly how it works.
How did you know?
And I suppose it's that computer scientistmindset, isn't it, of how you store
stuff?
How would you do that?
And again, it's the same principlethat we've been talking about
today, data representation.
And yeah, just turning thatinformation, in this case a
taste or a smell, into numbers.
I'm sure I've read somewhere about, nottaste, but smell generators that they've
(18:25):
been experimenting with that you can passdigital data to and a smell will come out.
But I'm kind of hoping that they,that stays on the drawing board,
because imagine, imagine prankingyour friends with that if they had
a, smellable monitor that'd be fun.
I
it when students ask questionsand it doesn't often happen.
(18:47):
I just live for the day when I explainbinary to a Key Stage 3 class and somebody
puts their hand up and says, but you'veonly mentioned positive whole numbers.
You know, what about fractionsor what about negative numbers?
But I did get a question the other day.
I was doing representation and Italked about ASCII and a lad said,
So if you want to store a wholesentence, do you add up the numbers?
(19:09):
Oh.
So I thought that that's,that's an interesting.
Well, not misconception necessarily, buta thought of how, how it might be done.
And I'm wondering the reason thatnobody's ever asked that before.
We have a quite a high turnoverof students and sometimes I
repeat lessons from earlier inthe year if the class has changed.
And so normally I do firstlyrepresentation, everything stored as
(19:32):
a number, and then we do binary andI include things like binary flags.
So, you know if you numberstuff 1, 2, 4, 8, you can have
unique combinations of those.
And I think we'd donethat the week before.
So it was a slightly different sequence.
So we, I suppose he'd seen me addingnumbers together that represent different
things, and then he'd, he'd made theleap to the ASCII, which is interesting.
(19:55):
So it made me wonder whetheractually the order is more
important than I thought it was.
I thought in my head, storing everythingas a number and then numbers are
binary was the logical way to do it.
But whether that actually hasan impact on the learning,
I'm still thinking about that.
And I'd love that question to beasked of me in the classroom as
well, because I'm just I'm whirringaway in my head there thinking
(20:17):
what I could do with that question.
It's great when the kidsask those questions.
The answer is, of course, no, but It's, Icould lead on to hashing and check sums.
It's a check sum, isn't it?
So, Mm-Hmm.
We could talk about the problem oftransmitting data with integrity and the
idea that you could send the whole ASCIIsentence, but you could also add up all
(20:38):
the ASCII values and send the total.
Yeah, and we do a bit of
parity as well you know.
Yeah, and it's a bit like parity.
So, so you could explore those things withthat question, but I'm totally with you.
Students asking questions is the bestthing to happen in your classroom,
and I wish it would happen more.
And sometimes they ask thingsI'd never thought of myself.
(20:59):
So last year I was with a GCSEclass, we'd done adding binary and
this lad said, oh, can you, can youmultiply binary in the same way?
Now, I've, I've been doing computerscience for like 40 years and I'd
never thought, thought of that.
So we did it on the board exactlyas you would do with binary numbers.
So adding the zero and, and it worked.
(21:20):
And I thought, oh yeah, I don't knowwhy I'd not thought of that myself.
Yeah, why
wouldn't it work?
Because again, it's just aplace value number system.
So yeah, but it's notsomething you do a lot.
I had a question in the classpopped into Andy Colley's
classroom earlier in the week.
And he'll be on the podcast nextweek, and he was doing a little bit of
(21:41):
programming at the end of the lesson, andI like the idea of doing a little bit of
programming at the end of every lesson,which is what Andy does, and it was his
year 10 class, and we were talking, Idon't know how we got on to it, but.
Oh yeah, some website had a roundingerror on it, and I said, oh, just do this.
0.
1 times 3 in the Python shell.
0.
1 times 3 in the Pythonshell, and it came up 0.
(22:05):
30000006 or something, so a binaryrounding error, and we got on to why that
works, and suddenly year 10 are beingtaught binary fractions, and getting it,
you know, and it was a fun diversion.
Oh, that sound meansit's competition time.
In episode one, I asked you topromote the pod on your socials and
(22:27):
someone who did just that is Mrs.
Bowen, AKA.
Tech craft girl on Twitter.
who wins a copy of how toteach computer science.
In episode two, I set a riddle andlet's hear a sneak preview of next
week's episode to hear the solution.
I just wondered if you had ananswer to my riddle last week.
So if I made a binary worksheet, Andy,and accidentally guillotined off the right
(22:51):
hand edge, it wasn't really important.
Why was that?
The right hand edge, not reallya significant bit, is it?
Yeah,
there you go.
, I've just cut off the least significantbit of all my binary numbers.
Well as Andy Colley on next week'sepisode with the answer, on the socials,
(23:15):
the first correct answer was from Mr.
Pete Dring, who wins a book and I'll begetting Pete on the pod sometime soon.
This week's competition is backto shameless self promotion.
If you have one of my books,you can enter the prize draw.
If you review it on Amazon, the prizeis the other book if you don't have
it, or if you have both books well doneyou, thank you for supporting my work,
(23:35):
you can have some lovely merch an HTTCSmouse mat, mug and pen can be yours.
Plus a shout out on thepodcast in a couple of weeks.
So give me a review onAmazon and win a prize.
Amazon links are at httcs.online/books.
So let's get back to today'sdiscussion with Andrew Virnuls.
(23:58):
We were talking earlier about bit depthand sample rate before we came on air
and how those things are kind of thesame across images, text, and sound.
This is something I try to make clearthat the number of samples per second
in a sound file is similar to theresolution of an image file or, bit
(24:19):
depth the number of bits you are allowedto play with for a text character
is similar to the number of bits perpixel or bits per sample in sound.
So is that a concept thatit's important to get across?
I think so, and I recently made a page forthe website which is in the math section.
I think it's called a range of binaryvalues because in the space of one week
(24:40):
I found myself effectively teaching thesame thing but in different contexts.
So there was the sample sizeand the color depth, but also
we were doing truth tables.
So the number of rows in the truthtable for a given number of inputs was,
is basically the same thing, isn't it?
So you've got three inputs, you needeight rows, and also again nested loops.
So if you had three nested loops, eachlooping through values of zero and one,
(25:06):
then that effectively gives you a threebit binary counter with eight rows.
So there's that idea of effectivelycombinations, and students are quite okay
with that idea if you explain it like, youknow, if they've got a combination lock on
their bike and they're familiar with theidea if you put an extra digit on there
it makes it more complex, but there'sthat, there's that idea, there's that
(25:27):
misconception, isn't it, that twice asmany bits gives you twice as many values.
Yeah, yeah.
I've seen that misconception in severalplaces where you know, bit depth being
the number of colors in an image,or color depth being the number of
potential colors in an image, when ofcourse it's just the number of bits,
and you have to raise two to the powerof the number of bits to get the number
(25:48):
of combinations, which is of coursetrue across text, images, and sound,
which is kind of the point I'm making.
Any more tips on teachingthis whole topic?
We were talking about when to teachthis topic earlier, weren't we?
So what would you sayabout when to teach it?
I suppose they're allinterlinked, isn't it?
One of the things I quite likeabout computing compared with
(26:09):
ICT is ICT seemed to be a bitof a random selection of stuff.
You know, like one day you weremaking a spreadsheet, the next
day you were reviewing a website.
But you've got theseoverarching ideas in computing.
the two state thing.
So storage, you've got two states.
Most storage media rely on You know, soyou've got your north and your south and
your magnetic storage and things reflect,or they don't reflect, or back in the
(26:31):
days of paper tape, a hole or no hole.
So that you can link that to the binary.
So I tend to do that first, because Isuppose that you need to think about
where this stuff is actually going to go.
Then I say computers onlyreally deal with numbers.
And then I go on to the numbersare stored in binary form, but I
do that early on first term becauseactually, you know, then that idea of
(26:56):
representation goes across everything.
So you do networking.
Well, what's in your network packet?
How do you address it?
they're all kind of forms ofrepresentation, aren't they?
Yeah, there's a link there.
I like what you said about theoverarching themes of computing
which I never really thought aboutit, but you're right, ICT is just.
A load of random stuff.
(27:16):
I quite like the way you can goback and revisit stuff as well.
So you can do binary, you can do Booleanlogic, and then if you so choose, you
can combine the two to do bitwise logicwhich is really not any, extra thing.
It really is just a combination, isn'tit?, I don't hear much about bitwise
logic these days, but it's somethingthat we do at Key Stage 3 because
there's that thing in the NationalCurriculum that says operations on
(27:39):
binary numbers, when I first read that.
Because it was in there with thebinary and the Boolean logic, my first
thought was bitwise logic because thatwas something we did when I was in
school and actually it's quite useful.
So if you want to write a programthat converts to binary, for example,
I would do that using bitwise logic.
So you do, you know, AND 1 for yourend digit and then AND 2 for the
(28:01):
next digit and AND 4 and so on.
So practically, it's a useful thingbecause the thing about computer science.
It's both a theoretical subject, isn't it,because you've got the written paper, but
also there's the practical aspects to it.
So those might not appear on papertwo in OCR, for example, but you might
want to use them to create a program,you know, in the evening or whatever.
(28:23):
Yeah, absolutely.
So we're going to runout of time about there.
It's been fantastic talking to you.
So it's Friday afternoon.
Are you done for the week, sir?
Just a little bit.
I'll do some backing up and stuff ofour, because I do the IT systems as
well, so I'm going to back up our lessonrecordings and registers and stuff.
(28:44):
It's been lovely to talk toyou, Andrew, on the podcast.
Well, thanks for having me.
You're welcome, and I'm going to askyou back in a few weeks to talk about
the GCSE qualifications, we can, at thatpoint, have a little reminisce about
Computer Studies O Level, which we bothsat in the 80s, that's right, isn't it?
That's right, and it's surprisinglysimilar, I find, to what we're doing now.
(29:07):
I was just
talking to someone about it AndyColley, who's going to be on next
week, and I was saying, I rememberin my computer studies O level exam
having to write a program in binary.
I don't know if you rememberdoing that, or just assembly
Language.
Opcodes and that kind of stuff.
(29:28):
Yeah,
opcodes and operands in binary.
so we will have a chat aboutthat in a few weeks, thank you
very much for coming in, Andrew.
Well, thank you.
We're out of time.
So let's revisit our fertile question.
What have braille andburger emojis got in common?
Have we answered it?
(29:48):
Let me know on the socials,this has been how to teach
computer science, the podcast.
I am Alan Harrison.
If you want to give me feedback or getinvolved, just go to HTTCS dot online.
Or check the show notes.
I'm also on threads,Mastodon, an X as mraharrison.
Or you can email me,Alan, at HTTCS dot online.
(30:11):
Remember, if you liked thiscontent, please subscribe, tell
your friends, buy my books, leavea review of my books on Amazon.
Or at the very least buy me acoffee details at HTTCS dot online.
So I'm off to change my passwordbecause I keep forgetting it.
So I'm going to changeit to the word incorrect.
Then if I forget it again,I'll get a nice little hint.
(30:32):
Unfortunately, we sometimeshave to pass a Captcha, you
know, prove you're not a robot.
I am so bad at them.
I mean, does this sliver ofbicycle tire count as a bicycle?
I feel like getting the guy whoinvented Captchas, sitting him down in
front of one that just says tick allthe squares without a tick in them.
And he can't leave until it's done.
That'll sort it.
Then you've got secret answer questions,which tempt my intrusive thoughts.
(30:53):
Like what's the name of your first pet?
And I type Sleipnir the mightySteed of Odin the All -father.
Is that just me?
Next week on how toteach computer science.
I will have special guest, Andy Colley,and we're talking all about pedagogy.
You're not going to want to miss it.
It's going to be a real groovy fella.
See you next week.
Welcome to how to teachcomputer science, the podcast.
This is episode three.
and we'll start with a fertile question.
What have Braylin burgeremojis got in common.
I'll be answering that questionand many more with the help
of today's special guest.
One of my old lecturers askedme what I thought for me
epitomizes computer science.
And at the time I said algorithmsthen went home and I thought about
(00:30):
it, actually I thought no, it'sdata representation isn't it?
Because it links everything together.
More on that at the moment.
My name is Alan Harrison, and I wrotethe books how to teach computer science
and how to learn computer scienceavailable in online bookstores, more
details at the companion website.
HTTCS dot online.
That's the initials of how toteach computer science.online.
(00:54):
If you like this content,please subscribe.
Tell your friends, buy my books.
Leave a review or buy me a coffee.
details at HTTCS dot online.
Every week, I'll transcribethis recording and blog it at
HTTCS to online slash blogs.
So, if you don't like my voice let'sbegin to answer our fertile question.
(01:19):
What have Braille andburger emojis got in common?
Let's start our story over in Paris,
not far from where Disneyland Paris nowstands, in the town of Coupvray, in the
leather workshop of La Famille Braille.
(01:43):
Louis Braille injured an eye inhis father's leather workshop
at the age of three, and theresulting infection caused him
to go blind in both eyes by five.
At age 10, he obtained a scholarship tothe Paris Institute for Blind Children.
which at the time used asystem of raised letters.
Braille found the system hard to learnand when he was shown a system of raised
dots used by the military to communicateat night, he took it and improved upon
(02:06):
it using just six dots to representall the letters of the alphabet, plus
numbers and some punctuation symbols.
Each dot is raised or flat and ablank space, effectively six flat
dots separates words and sentences.
In this way, the grid of six dotscould represent two to the power
of six or 64 different characters.
Braille is therefore a binarycode for representing text.
(02:27):
If we ordered the dots as Braille did fromone at the top left, finishing with six at
the lower right, then each of the Braillecodes can just as easily be written
out as a sequence of bumps and flats.
So A is bump, flat,flat, flat, flat, flat.
And H is flat, bump,bump, bump, flat, flat.
Replacing bump with one and flat withzero we can write A as 100000, and H
(02:50):
as 011100, We can now write any textusing just two digits, zero and one.
Braille has created a binary codeto represent text, and electronic
computers have not yet been invented.
Fast forward to 1961, when IBM engineerBob Bemer proposed a single code for
computer communication and two yearslater announced the American Standard
(03:12):
Code for Information Interchange or ASCII.
ASCII is a lookup table thattranslates letters and punctuation
marks to numeric codes.
A character set thus enables thestorage and processing of text by a
digital computer, which also meansdata created on one computer can
be processed by another computer.
Originally a 7 bit code representingonly 128 unique symbols, international
(03:36):
popularity demanded more characters.
Various 8 bit versions, oftencalled extended ASCII, were popular
in the 1970s and 1980s, with an8 bit standard emerging in 1987.
Computer makers standardized on 8 bitbytes in the early 1970s, so the extended
ASCII character set made perfect sense.
But the 256 different bit patternsavailable from 8 bits were not
(03:57):
enough for languages such as arabic,
مرحبا
السلام عليكم
Chinese
and Japanese.
Konnichiwa.
and the Unicode standardwas inaugurated in 1991.
Originally a 16 bit code givingover 65 000 characters, a later
version called UTF 8 allows up to32 bits per character, which has
given room for all modern languages.
(04:18):
Unicode opened up the internetto non English speaking peoples
who had previously been forcedto work in European languages.
And in that sense, the UniversalCharacter Set was an important leveller.
As Unicode consortium lawyer AndyUpdegrove put it in a 2015 interview,
(04:43):
so why does all that linkbraille and burger emojis?
Well in each case real world informationhas been encoded into binary.
Braille is a 6 bit binary code, and emojisare part of the Unicode 32 bit standard.
This is all part of the computerscience topic of data representation.
At the heart of this topic isthe idea that if we can turn
information into binary data, wecan use a computer to process it.
(05:08):
Digital computers processbinary numbers because they use
two state electrical signals.
The challenge is therefore tofind a transformation from real
world information to binary.
This transformation is calledencoding, and it makes use of a code.
ASCII and Unicode are used to encode text.
JPEG, GIF, and PNG do the samefor bitmap images, and WAV, MP3,
(05:28):
and AAC encode digital sound
Ding!
as predicted by a brilliantyoung mathematician, more
than a hundred years ago.
(05:58):
But it's important to realize thatthere are virtually limitless ways of
encoding information, and these arejust the techniques that are widely
used owing to their effectiveness,or official recognition, or both.
That's really the fundamentalsof data representation covered.
The most important concept is weneed a way of encoding information
as binary, and then we've cracked it.
(06:18):
You can read more about datarepresentation in my book,
How to Teach Computer Science.
I am delighted to say it's notjust me rambling on today because I
have a special guest in the studiotoday hello to the man behind
advanced-ict.Info welcome, Andrew Virnuls.
(06:39):
How are you, sir?
Very well, thank you.
Good to have you on the podcast.
So you were listening to allthat, was that a reasonable
intro to data representation?
It was, and it made me think thatthat idea of the combinations is also
an important idea, isn't it, acrosscomputer science from things like,
how many rows you got in your truthtable, to the width of your data bus,
(07:01):
to colour depth, and in fact the waythat you can actually make a binary
counter using nested loops as well.
Yeah, absolutely.
Can you just tell us where you work andwhat you do, Andrew, for the listeners?
So, I am lead teacher and computingspecialist for a service in Warwickshire,
local authority service for childrenout of school for medical reasons.
(07:22):
So, effectively like a hospitalschool, but Warwickshire
hasn't really got a hospital.
it's interesting.
It's got some challenges.
So we get students from schoolsall over the county with a variety
of, , backgrounds and prior learning,and all doing different courses,
possibly, and some having learneddifferent programming languages.
(07:42):
That sounds really fascinating.
I mean, There's a lot of teacherslistening, thinking, well, I've got quite
a diverse bunch of classes in my schooland then, and then there's you with
well, yeah, in the same class a coupleyears ago, I had students doing three
different boards in computer science,most of them doing Python, but one
of them doing visual Basic, whichmade demonstrations of programming
(08:04):
techniques quite interesting.
Luckily, the theory is quite similar,actually, between the GCSEs these days.
Yeah, no, that's true.
And you've got a website.
Let me get the address.
Right, advanced-ict.Info, otherwiseknown as computing and ICT in a nutshell.
That's you, isn't it?
That's right.
It used to be called ICT in a nutshellbecause I created it back in the ICT days.
(08:25):
And it started off with the databasessection because I used to find every
year the A level ICT students would askme the same questions about, you know,
normalizing their access databases.
But I've added the computingstuff over the years.
I did, I did toy with the idea of.
Changing the domain name but I thought,well, actually, you know, I think like BMW
still use the propeller, even though theydon't make aeroplanes anymore, don't they?
(08:47):
Oh, that's a good
point.
Yeah.
No, I have used, I've usedyour website in the classroom.
A number of times, there's somereally useful stuff on there.
I like the bitmap generator thingto demonstrate things like bit depth
and number of colors relationship.
And, and we were talking about thesound wave one recently, and you've
improved it after conversations with me.
(09:09):
I think sampling the sine waveI think that's really useful.
There's some great stuff on there.
So
the metadata one was the interestingone because we were talking about
misconceptions and I suppose it'snot quite a misconception, but I
found that the students didn't reallyremember what metadata was for.
So I added that you could uploada picture and basically it shows
the pixels but just arranged intoa square, so you have to kind of
(09:32):
rearrange them into the right widthand height to reconstruct the picture.
So knowing the colors of the pixelsisn't enough to reconstruct the picture.
You need to know howthey're arranged as well.
Yeah,
I like it.
I like it.
made a note that I wanted totalk about today the parallels
across different file types.
You know how things like bit depthis the same principle in JPEG
(09:56):
images as it is in digital audio.
So the number of bits in a sampleis the same concept, no matter
what sort of file you're in.
Yeah, so yeah, the other thing I thinkabout image representation is there's
obviously different types of things.
One of the things I'm never sure aboutwith GCSE, for example, is what we do
(10:18):
about palette based file formats like GIF,because it was an interesting question
a few years ago, and it was one of thosetrue or false tables, and one of the
statements was the color for the pixelis stored in metadata, and I thought,
oh what if the actual colours are in thepalette, which is presumably the metadata?
Yeah, that's a statement that couldeasily be misinterpreted, couldn't it?
(10:41):
And I think I've seen questions likethat, exam questions asking where the the
colors are stored, and I guess there'sa difference between the color of a
pixel and the colors in the palette.
So I guess the palette needs to be storedsomewhere, and that would be in metadata.
Yeah so all of this stuff, so.
WAVs or JPEGs or PNGs.
(11:03):
Underneath, it's justbinary noughts and ones.
So somewhere in data representation,when you're teaching it,
you have to teach binary.
So how, big question,how do you teach binary?
Well, what I tend to do is first of all,say everything's stored as a number and
then say the numbers are stored as binary.
And I don't know whether I'mgetting better at explaining binary.
(11:27):
or just whether students have moreexposure to it but find as time goes
on they seem to struggle less withit because if you look on my website
there's a number base abacus which Iused to use quite regularly and I say
well you know this is it with tens andhundreds and things and you would Slide
the beads across to represent certainnumbers then say what would happen if
you only had one bead on each row andcould we make a number that way and then
(11:50):
say well basically you take that abacusyou turn it on its side and those are
your columns and you know those are thesame as the binary digits but actually
I tend to find I don't need to do thatnow I can jump straight to the noughts
and ones and they they seem to get it.
That's interesting I mean I guessour colleagues down in primary are
teaching this now, so it's it's goodto know that it's coming through.
(12:11):
I like what you said about the abacus andif an abacus only had sort of one bead,
I always try to explain binary as justa place value number system in the same
way that denary or decimal is and I'm atgreat pains to go back and forth between
decimal and binary and to reinforce thenotion of place value because it's just
(12:32):
a different number base, but the numberswork exactly the same way as decimal.
So I go over that placevalue thing over and over
again.
I think that's very important to sayand in fact I start off by saying
actually if you want to communicatea number, say four, what's all the
different ways we could write that down?
We could write it in roman numerals ortally and binary is just a different
way of writing it down effectively.
(12:54):
But actually the first slide of thepresentation that I use, because I know
PowerPoint's a bit out of fashion, Iteach mainly online, I don't know if
the listeners know that, so we haveto have something that they can see.
Trust me, PowerPoint is not going anytimesoon, but I know exactly what you mean.
I teach a lot less on PowerPoints now,but yeah, sometimes you need them.
Sorry,
(13:14):
carry on.
So my first slide is literally justa reminder of how denary works,
because I think that when you usesomething so often, you tend to
stop thinking about how it works.
So I'll show them why it's basedon tens, and the fact, you know,
as you move across, the placevalue increases by a factor of 10.
And in each position, you canhave one of 10 possible digits.
(13:35):
And then I repeat that slide when we lookat binary, and I use the same slide, I
just replace the word ten with two andthen replace the word two with 16, but
and then I also show them other things.
So in the same way that99 is one less than 100.
So effectively the largest valueyou can have in a given number
of digits is one less than thefirst unused column in that 111.
(13:58):
You could say, well, that's four plustwo plus one, or it's one less than
eight, which is the first empty column.
And then also the shifting idea.
So if you move numbersone place to the left.
They get 10 times bigger, if youdo it with binary, they double.
So it's about making it appear consistent.
I think that's the,that's the thing for me.
So I said in my intro to the podcast thatif we can turn information into binary
(14:21):
data, we can use a computer to process it.
And I called that encoding.
So we just need a different encodingmethod for different types of data.
So ASCII and Unicode are a way of encodingtext, how do you go about teaching
ASCII and Unicode in the classroom?
Well, I just, start off with everythingthat needs to be stored as a number.
(14:42):
So how do you think wecan, how can we store text?
And actually.
That's probably the most straightforwardof all of them in terms of the
students being able to understand.
So I just show them anASCII table and say, look,
everything's got its own number.
Sometimes they struggle with the idea thatuppercase letters and lowercase letters
are different, but I point out that that'sactually why, if you write in your Python
(15:05):
program and you say, you know, do you wantto continue y or n and they put a capital
Y, that's why it doesn't recognize it.
Whereas Google doesn't care orAccess or Excel tend not to care
in their searches because actuallyit's checking the aSCII values.
And similarly, when you sort thingsinto order obviously letters are, in
alphabetical order, but also things likepunctuation marks and stuff get sorted
(15:29):
into that order as well, presumablybased on the ASCII value of, those
symbols.
Yeah, no, that's a good point, and Ihadn't really thought of mentioning
things like sorting in algorithmsat this point when teaching ASCII,
but it's a good link to make.
So if we can get things intonumbers, we can process them.
So, Images.
(15:51):
Thinking of JPEG and so on, this isone of my favourite topics to teach.
Do you get the graph paper gridsout and get them to colour in?
Do you do colouring in whenyou're teaching images, Andrew?
I don't because I don't physically seea lot of our students, but I have, there
is a, there is a page on my website wherethey can click and color in the dots.
(16:11):
And I do explain that like,like knitting patterns as well.
You can kind of knit things withdifferent color stitches or cross
stitch that might be familiar with.
Yeah,
So there's a story in the book.
Did I mention I wrote a book?
There's a story in the book aboutthe woman who created the first
(16:31):
icons for the Apple Macintosh,and she was a cross stitcher.
Susan Kare, and she was hired tocreate some striking fonts and
icons for the Apple Macintosh.
So it's her fault you've got thebomb emoji and things on a, on a Mac.
But she was a cross stitcher and so itwas exactly the same principle of creating
images with just a grid of pixels.
(16:55):
It's interesting that idea as well.
You know, people say, whydo you need to know this?
But I think it kind of demystifies theprocess of editing images and things.
And that's why I created the page onmy website where you can upload a photo
and it pulls out the numbers of, youknow, the amount of red, green, and
blue, and you can add or subtract fromthose numbers and see the impact on
the image, and then you realize, like,Photoshop's really just arithmetic.
(17:17):
But then once you start thinking about howthings are stored, so one of the things
I say to the students is basically, ButComputers only deal with numbers so if you
want to store a new type of informationyou need to think about how you can
measure and store that as a number andI used to give the example of smell for
example so you know something unfamiliaryou need to think about how you do that
and then about two or three weeks agomy wife was reading the news one evening
(17:39):
and she said oh Apparently there's thisnew screen where you can lick it and
you can taste what's being displayedand my first thought was obviously
but I hope it's a personal device.
But secondly was, I thought,well, how does that work?
I said, could you,could you make a flavor?
By mixing together amounts of,you know, saltiness and sourness
and bitterness and umami.
(17:59):
And she went, yes, that'sexactly how it works.
How did you know?
And I suppose it's that computer scientistmindset, isn't it, of how you store
stuff?
How would you do that?
And again, it's the same principlethat we've been talking about
today, data representation.
And yeah, just turning thatinformation, in this case a
taste or a smell, into numbers.
I'm sure I've read somewhere about, nottaste, but smell generators that they've
(18:25):
been experimenting with that you can passdigital data to and a smell will come out.
But I'm kind of hoping that they,that stays on the drawing board,
because imagine, imagine prankingyour friends with that if they had
a, smellable monitor that'd be fun.
I
it when students ask questionsand it doesn't often happen.
(18:47):
I just live for the day when I explainbinary to a Key Stage 3 class and somebody
puts their hand up and says, but you'veonly mentioned positive whole numbers.
You know, what about fractionsor what about negative numbers?
But I did get a question the other day.
I was doing representation and Italked about ASCII and a lad said,
So if you want to store a wholesentence, do you add up the numbers?
(19:09):
Oh.
So I thought that that's,that's an interesting.
Well, not misconception necessarily, buta thought of how, how it might be done.
And I'm wondering the reason thatnobody's ever asked that before.
We have a quite a high turnoverof students and sometimes I
repeat lessons from earlier inthe year if the class has changed.
And so normally I do firstlyrepresentation, everything stored as
(19:32):
a number, and then we do binary andI include things like binary flags.
So, you know if you numberstuff 1, 2, 4, 8, you can have
unique combinations of those.
And I think we'd donethat the week before.
So it was a slightly different sequence.
So we, I suppose he'd seen me addingnumbers together that represent different
things, and then he'd, he'd made theleap to the ASCII, which is interesting.
(19:55):
So it made me wonder whetheractually the order is more
important than I thought it was.
I thought in my head, storing everythingas a number and then numbers are
binary was the logical way to do it.
But whether that actually hasan impact on the learning,
I'm still thinking about that.
And I'd love that question to beasked of me in the classroom as
well, because I'm just I'm whirringaway in my head there thinking
(20:17):
what I could do with that question.
It's great when the kidsask those questions.
The answer is, of course, no, but It's, Icould lead on to hashing and check sums.
It's a check sum, isn't it?
So, Mm-Hmm.
We could talk about the problem oftransmitting data with integrity and the
idea that you could send the whole ASCIIsentence, but you could also add up all
(20:38):
the ASCII values and send the total.
Yeah, and we do a bit of
parity as well you know.
Yeah, and it's a bit like parity.
So, so you could explore those things withthat question, but I'm totally with you.
Students asking questions is the bestthing to happen in your classroom,
and I wish it would happen more.
And sometimes they ask thingsI'd never thought of myself.
(20:59):
So last year I was with a GCSEclass, we'd done adding binary and
this lad said, oh, can you, can youmultiply binary in the same way?
Now, I've, I've been doing computerscience for like 40 years and I'd
never thought, thought of that.
So we did it on the board exactlyas you would do with binary numbers.
So adding the zero and, and it worked.
(21:20):
And I thought, oh yeah, I don't knowwhy I'd not thought of that myself.
Yeah, why
wouldn't it work?
Because again, it's just aplace value number system.
So yeah, but it's notsomething you do a lot.
I had a question in the classpopped into Andy Colley's
classroom earlier in the week.
And he'll be on the podcast nextweek, and he was doing a little bit of
(21:41):
programming at the end of the lesson, andI like the idea of doing a little bit of
programming at the end of every lesson,which is what Andy does, and it was his
year 10 class, and we were talking, Idon't know how we got on to it, but.
Oh yeah, some website had a roundingerror on it, and I said, oh, just do this.
0.
1 times 3 in the Python shell.
0.
1 times 3 in the Pythonshell, and it came up 0.
(22:05):
30000006 or something, so a binaryrounding error, and we got on to why that
works, and suddenly year 10 are beingtaught binary fractions, and getting it,
you know, and it was a fun diversion.
Oh, that sound meansit's competition time.
In episode one, I asked you topromote the pod on your socials and
(22:27):
someone who did just that is Mrs.
Bowen, AKA.
Tech craft girl on Twitter.
who wins a copy of how toteach computer science.
In episode two, I set a riddle andlet's hear a sneak preview of next
week's episode to hear the solution.
I just wondered if you had ananswer to my riddle last week.
So if I made a binary worksheet, Andy,and accidentally guillotined off the right
(22:51):
hand edge, it wasn't really important.
Why was that?
The right hand edge, not reallya significant bit, is it?
Yeah,
there you go.
, I've just cut off the least significantbit of all my binary numbers.
Well as Andy Colley on next week'sepisode with the answer, on the socials,
(23:15):
the first correct answer was from Mr.
Pete Dring, who wins a book and I'll begetting Pete on the pod sometime soon.
This week's competition is backto shameless self promotion.
If you have one of my books,you can enter the prize draw.
If you review it on Amazon, the prizeis the other book if you don't have
it, or if you have both books well doneyou, thank you for supporting my work,
(23:35):
you can have some lovely merch an HTTCSmouse mat, mug and pen can be yours.
Plus a shout out on thepodcast in a couple of weeks.
So give me a review onAmazon and win a prize.
Amazon links are at httcs.online/books.
So let's get back to today'sdiscussion with Andrew Virnuls.
(23:58):
We were talking earlier about bit depthand sample rate before we came on air
and how those things are kind of thesame across images, text, and sound.
This is something I try to make clearthat the number of samples per second
in a sound file is similar to theresolution of an image file or, bit
(24:19):
depth the number of bits you are allowedto play with for a text character
is similar to the number of bits perpixel or bits per sample in sound.
So is that a concept thatit's important to get across?
I think so, and I recently made a page forthe website which is in the math section.
I think it's called a range of binaryvalues because in the space of one week
(24:40):
I found myself effectively teaching thesame thing but in different contexts.
So there was the sample sizeand the color depth, but also
we were doing truth tables.
So the number of rows in the truthtable for a given number of inputs was,
is basically the same thing, isn't it?
So you've got three inputs, you needeight rows, and also again nested loops.
So if you had three nested loops, eachlooping through values of zero and one,
(25:06):
then that effectively gives you a threebit binary counter with eight rows.
So there's that idea of effectivelycombinations, and students are quite okay
with that idea if you explain it like, youknow, if they've got a combination lock on
their bike and they're familiar with theidea if you put an extra digit on there
it makes it more complex, but there'sthat, there's that idea, there's that
(25:27):
misconception, isn't it, that twice asmany bits gives you twice as many values.
Yeah, yeah.
I've seen that misconception in severalplaces where you know, bit depth being
the number of colors in an image,or color depth being the number of
potential colors in an image, when ofcourse it's just the number of bits,
and you have to raise two to the powerof the number of bits to get the number
(25:48):
of combinations, which is of coursetrue across text, images, and sound,
which is kind of the point I'm making.
Any more tips on teachingthis whole topic?
We were talking about when to teachthis topic earlier, weren't we?
So what would you sayabout when to teach it?
I suppose they're allinterlinked, isn't it?
One of the things I quite likeabout computing compared with
(26:09):
ICT is ICT seemed to be a bitof a random selection of stuff.
You know, like one day you weremaking a spreadsheet, the next
day you were reviewing a website.
But you've got theseoverarching ideas in computing.
the two state thing.
So storage, you've got two states.
Most storage media rely on You know, soyou've got your north and your south and
your magnetic storage and things reflect,or they don't reflect, or back in the
(26:31):
days of paper tape, a hole or no hole.
So that you can link that to the binary.
So I tend to do that first, because Isuppose that you need to think about
where this stuff is actually going to go.
Then I say computers onlyreally deal with numbers.
And then I go on to the numbersare stored in binary form, but I
do that early on first term becauseactually, you know, then that idea of
(26:56):
representation goes across everything.
So you do networking.
Well, what's in your network packet?
How do you address it?
they're all kind of forms ofrepresentation, aren't they?
Yeah, there's a link there.
I like what you said about theoverarching themes of computing
which I never really thought aboutit, but you're right, ICT is just.
A load of random stuff.
(27:16):
I quite like the way you can goback and revisit stuff as well.
So you can do binary, you can do Booleanlogic, and then if you so choose, you
can combine the two to do bitwise logicwhich is really not any, extra thing.
It really is just a combination, isn'tit?, I don't hear much about bitwise
logic these days, but it's somethingthat we do at Key Stage 3 because
there's that thing in the NationalCurriculum that says operations on
(27:39):
binary numbers, when I first read that.
Because it was in there with thebinary and the Boolean logic, my first
thought was bitwise logic because thatwas something we did when I was in
school and actually it's quite useful.
So if you want to write a programthat converts to binary, for example,
I would do that using bitwise logic.
So you do, you know, AND 1 for yourend digit and then AND 2 for the
(28:01):
next digit and AND 4 and so on.
So practically, it's a useful thingbecause the thing about computer science.
It's both a theoretical subject, isn't it,because you've got the written paper, but
also there's the practical aspects to it.
So those might not appear on papertwo in OCR, for example, but you might
want to use them to create a program,you know, in the evening or whatever.
(28:23):
Yeah, absolutely.
So we're going to runout of time about there.
It's been fantastic talking to you.
So it's Friday afternoon.
Are you done for the week, sir?
Just a little bit.
I'll do some backing up and stuff ofour, because I do the IT systems as
well, so I'm going to back up our lessonrecordings and registers and stuff.
(28:44):
It's been lovely to talk toyou, Andrew, on the podcast.
Well, thanks for having me.
You're welcome, and I'm going to askyou back in a few weeks to talk about
the GCSE qualifications, we can, at thatpoint, have a little reminisce about
Computer Studies O Level, which we bothsat in the 80s, that's right, isn't it?
That's right, and it's surprisinglysimilar, I find, to what we're doing now.
(29:07):
I was just
talking to someone about it AndyColley, who's going to be on next
week, and I was saying, I rememberin my computer studies O level exam
having to write a program in binary.
I don't know if you rememberdoing that, or just assembly
Language.
Opcodes and that kind of stuff.
(29:28):
Yeah,
opcodes and operands in binary.
so we will have a chat aboutthat in a few weeks, thank you
very much for coming in, Andrew.
Well, thank you.
We're out of time.
So let's revisit our fertile question.
What have braille andburger emojis got in common?
Have we answered it?
(29:48):
Let me know on the socials,this has been how to teach
computer science, the podcast.
I am Alan Harrison.
If you want to give me feedback or getinvolved, just go to HTTCS dot online.
Or check the show notes.
I'm also on threads,Mastodon, an X as mraharrison.
Or you can email me,Alan, at HTTCS dot online.
(30:11):
Remember, if you liked thiscontent, please subscribe, tell
your friends, buy my books, leavea review of my books on Amazon.
Or at the very least buy me acoffee details at HTTCS dot online.
So I'm off to change my passwordbecause I keep forgetting it.
So I'm going to changeit to the word incorrect.
Then if I forget it again,I'll get a nice little hint.
(30:32):
Unfortunately, we sometimeshave to pass a Captcha, you
know, prove you're not a robot.
I am so bad at them.
I mean, does this sliver ofbicycle tire count as a bicycle?
I feel like getting the guy whoinvented Captchas, sitting him down in
front of one that just says tick allthe squares without a tick in them.
And he can't leave until it's done.
That'll sort it.
Then you've got secret answer questions,which tempt my intrusive thoughts.
(30:53):
Like what's the name of your first pet?
And I type Sleipnir the mightySteed of Odin the All -father.
Is that just me?
Next week on how toteach computer science.
I will have special guest, Andy Colley,and we're talking all about pedagogy.
You're not going to want to miss it.
It's going to be a real groovy fella.
See you next week.
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