[Music]
Good day and welcome to my talk, Why
Teach the Y. Um, we're going to talk
about how context empowers learning, and
about how carving out time to dedicate
to context, improves outcomes, and can
reduce the time that you have to spend
on revision.
Um, let's start with who I am and why
I'm giving this talk. Uh, I'm Jack. You
probably got that already. Um, I'm the
CTO and co-founder of Kumo Study. We
make uh study management tools for
learners with ADHD and tools for
institutions to support them. Um, and
I'm a computer science educator. I have
a decade of experience teaching at camps
and workshops and incursions as well as
I spent two years teaching at a high
school in Sydney.
I want to kick things off with a little
scenario that I think all of the
educators in the room here have probably
experienced. Don't worry too much about
the specifics. It's more just the
general shape of the scenario. So, you
spend some time teaching, say, databases
or some other topic to your students and
it seems like they understand it and
it's all going pretty well. And then you
move on to another topic, say cyber
security or electronics. Again, they're
understanding it and things are going
well.
And then a student asks how they're
related.
Or for another example, suppose you're
teaching a topic that you know
necessitates a bit less time, maybe
image file formats or different storage
technologies and you cover what's
discussed in the curriculum
and then you move on to the next topic
and then come time for the assignment or
the exam, it seems like the students
have more or less forgotten everything
about that topic.
These scenarios highlight the only
problem with the curriculum.
shared by computer.
Of course, you try and put them in a
sensible, cohesive order, but there is
only so much that can be done.
This leads to students feeling like the
course is a mishmash of different
elements unrelated to each other. And
this in turn leads to students having a
hard time building a strong mental model
of the course. And so more time has to
be spent on revision further cutting
into time to cover the curriculum. So
what can you do about it? Well, context
is critical.
I have found that when I spent more time
on context, I was able to mitigate those
problems to quite a considerable degree.
I actually spent very little time on
revision. Only a couple of handful, only
a handful of weeks across all of 9 and
10. And even then, with very little
prompting, the students themselves
actually provided the solutions for the
initial examples I worked through on the
board before I handed out revision
sheets or cheat sheets or went through
it again with them. But most
importantly, I found that students grew
more engaged and excited by our classes.
They were very motivated to join in on
class discussions. They always wanted to
know more and they became excellent at
connecting disperate topics together.
So, let's clear up what I mean by
context here. Since it's a bit of an
ambiguous word, it could really mean
almost anything you want it to mean.
What I mean at its core is why is this
the way that it is? The answers to this
question vary wildly depending on the
topic at hand. There's historical and
social reasons. There's limitations of
technology of when the topic was
developed. And sometimes it's just the
plain physics of the universe.
I always ask myself and I encourage my
students to ask why did
uh why did the people making this
technology system standard or whatever
do it this way? People by and large
don't do things for no reason.
They may have a bad reason, but even a
bad reason
helps you understand.
For example, you've
on. It was the age of wisdom. It was the
age of foolishness.
He continues further. It was the epoch
of belief. It was the epoch of
incredility.
Light and darkness, hope, despair. On
and on he goes.
He's supposed to be this great writer
and certainly best of times, worst of
times is a banger of a line. But why
does he just keep going, driving his
point into the ground? We get it. Things
were both one way and the other way at
the same time. London is two cities at
once.
Why are you like this? Well, Dickens was
paid by the word.
And suddenly all of that makes sense,
doesn't it? And odds are much slimmer
that you'll forget either that he was
paid by the word or that there is much
more after that famous line.
So I do this in class
with Python including using multiple
conditions in an if statement and we
moved on to logic gates and boolean
algebra. So multiple conditions in an if
statement and they were getting it but
not as quickly or as well.
And I realized that the problem was that
all the exercises, even when wrapped up
in a scenario or a story, just kind of
look like this. And it's just shapes on
a page.
I knew that it
used
that circuitry build
of course. So I decided it was time to
stop doing abstract problems and start
building a computer in from scratch.
As a reminder, these kids are in grade
nine.
So, we start out with the simplest thing
that I could think of that could be
called a computer, a one bit adder. It
takes in two one bit numbers and it adds
them together, making a new two-bit
number.
So, I explained what we were doing and
together we drew up a truth table for
the one bit adder and I told them I told
them to design a logic circuit that
replicated this truth table. And they
all made things that looked roughly like
this.
Once they did that, I congratulated them
on having built a computer from scratch.
It seems silly, but they genuinely had.
This wasn't an abstract puzzle. This
wasn't just plugging numbers into a
design.
So,
I escalated.
I said, "Okay, we're going to make a
bit." Now, we can't quite just copy what
we did because we've got that carry bit
coming in from the one bit adder.
So, we had to make a new truth table
that accounted for that and then design
a new circuit. And so, we made a one bit
full adder.
Once we had that, then we just had to
glue two of them together like so.
And then you can glue two of those
together and two of those together. And
now you've got a one bite adder. So now
we're really cooking with gas. We've
designed a computer that can take any
two numbers between 0 and 255 and add
them together. And that's pretty cool
for a bunch of nicates
and if they wanted they could go and buy
some buttons and wires and more gates
and they could build the design that I
had that they had just made and it would
work. I think actually doing that in
class would have been a great thing to
do but unfortunately I didn't quite get
around to it. next time hopefully
by the end
uh and and then we continued on. We kept
expanding this computer adding more
features and functionality to it. By the
end it could add and subtract bytes
using two's complement.
Uh you could put the result into one of
either two bytes in memory. um and it
could be given an instruction consisting
of two bytes of data whether to add or
subtract them and which memory address
to store the result in. So this is
genuinely a computer with no hint of
exaggeration. I showed them how you can
take the binary for that input there and
that's called an op code and this is the
basis of machine language. That's what
assembly languages directly translate
into. It's what Python indirectly
becomes. All told, we spent most of term
two in grade 9 working on these computer
designs. And then after their assignment
was done, we did not touch logic gates
again until term three of year 10. So
over a year later,
guess what? They remembered it pretty
well. They weren't entirely certain of
which symbols were which gates
but they were largely correct on that
and they knew how to make a truth table
and make a circuit and they knew how to
take a circuit and make the truth table
from that. They knew how to actually use
the logic gates in a way that I only
ever learned in university.
This also works with smaller topics. So,
I was teaching the Cambridge IGCSE
curriculum and according to it, there's
only one thing you need to know about
sound files. So, you're getting the
inside scoop on what that whole
curriculum covers there. Sound files
have a sample rate and a higher sample
rate.
Congratulations, you've graduated.
So that's just one sentence and you can
probably memorize it pretty easily. But
memorization I feel isn't a satisfying
learning experience. It's not going to
enuse the students and it's prone to
being forgotten. So I
sample rate and why does it make a
higher quality sound?
Before I could answer that, I had to ask
what even is a sound? I forgot to click
through my slides.
Sound is the vibration of particles in
air. And we can represent that vibration
with waves.
A single a simple sound of just a single
note is a nice sine wave.
speakers in controlled by an
electromagnet to push the air in the
same pattern. And so this complex wave
or even the simple wave in fact shows
the position of the speaker at any
moment in time.
And that and the sample rate is how
often we check where the speaker should
be.
If we go back to the simple example,
we've got just a single note here at 500
htz.
This graph just shows an 8 slice of it.
At one extreme of sampling, we have the
perfect sample.
This is if we could somehow sample every
infinite decimal slice of this graph and
then we can reproduce the sound.
But then if we're going to store this
digitally, then that requires infinite
digital storage space. Um, and I don't
have that.
So let's jump to the other extreme and
go for a very low sample rate. Um, you
can see our original signal in blue
here. And if we sample the note at the
same frequency, 500 times a second, uh,
we get that red line here. Um, so it's
always at zero and the speaker doesn't
move.
So that's not going to be enough.
If we go just a little bit more
frequently, say 502 times a second, we
can see that we've got a sample that
slowly moves the speaker.
Um, this is clearer to see what it's
doing wrong. If we expand this view out
to a whole second of the soundwave,
we've got our original soundwave at 500
Hz still in blue, and we've got what
comes out of our sample here. And that's
definitely not the same note as the blue
wave. Uh that's only about 2 herz
but actually produce a sound
triangular wave pattern. So it will
still sound weird and robotic but at
least it is the right pitch. Now,
it will also struggle with a more
complex sound wave. You can see that
much of this wave gets cut off and so
the sound is going to be heavily
distorted.
So, we need the sample rate to be at
least four times the frequency of the
highest sound that we want to record.
Human hearing range is generally between
15 to 20 kHz, but the top end of that
isn't commonly used in audio files or
music. Um, the highest note on a piano
is just under 8 kHz. So, we'd need a
sample rate of at least 32 kHz. We can
go higher for smoother, more natural
sounds, as well as to accommodate uh the
top ends of the hearing range. So, audio
is commonly recorded at 44.1 kHz or 48
kHz. This graph shows here an 8 kHz
sound recorded at 44.1. And you can see
that it's not perfect. You do get little
clipped edges on a lot of the waves, but
overall it's a pretty close match.
Now, in class, I actually went through
all of these graphs with my students. We
saw what the sample rate was. We saw how
it impeds
behind it. We covered this over a single
lesson. It didn't take much longer than
I just spent with you. Um,
and we covered this in the first few
weeks of grade 10 and then we didn't
discuss it until for the rest of the
year.
All of them got this question right on
their final exam though. I didn't I
didn't discuss it again since then. We
didn't revise it. Nobody asked me about
it. They all got it right.
But I wanted to emphasize the kind of
approach that I take in these
discussions really exploring the space
and uncovering that context. But how do
I achieve this? Am I just some kind of
super genius who knows everything? No, I
use Wikipedia loads.
Um, I don't want to be too flippant
here, but I cannot overstate how good
Wikipedia is.
Let's take a look at the Wikipedia page
for audio file format. It's got a bunch
of stuff here that seems well out of my
depth, but if we scroll down or if we
search the page, hey, it says sample
rate. And I knew from the line in the
textbook that that was the thing that we
cared about. So, let's click that and go
to that page.
and we're going to check out this
article and it goes into more detail
than I did, but it covers a bunch of the
same stuff. You can see there that graph
not too dissimilar from the kind of
graphs that I was drawing.
So, with just two pages on Wikipedia, we
can get a decent idea of what a sample
rate is and then convey that explanation
to our students.
This is true for pretty much every
technical topic. Um
I I think largely because Wikipedia has
come you know has come up in the age of
computers fairly obviously. Um it has a
lot of stuff about computers and about
computer science and everything on it.
So if you are teaching computer science
at all it is an excellent source to
learn about the context and the history
and the why things were done the way
they were.
The other two big
enough to make it real.
A few little tidbits to tie it to the
context is entirely sufficient.
All that matters is that there is enough
there for them to latch on to and go,
"This is something that impacts the real
world. This is something that a real
human being put thought into. Maybe not
a lot, but they put some thought into it
and they made it and there were reasons
behind what they did.
The other big one, involve your
students. You can give them research
tasks or have an open discussion. I
found asking why do you think they made
it like that is a great way to get a
discussion going. Um, this Oh no, I
pressed a button because I dropped the
thing.
Why do you think they made
Why do you think they made it like that?
That is a good question. Why is there a
button right under where your thumb sits
that exits the whole presentation?
Um,
yes, maybe not a good reason. Um,
so a an excellent example I had of this
was um well I I found that this worked
particularly well for topics that are
maybe a little controversial. Not you've
got to it pick the right ones but a
little controversial or current or
there's a lot of ambiguity floating
around. We had a great discussion in
class about NFTTS. I explained what they
were, how they worked. I explained
blockchain and how that worked and
there was and I asked them, you know,
why do why do you think NFTts work like
this? And there was a pause and one of
them said, it just seems like gambling.
And I said, okay, go on. and she said,
"Well, it just seems like the only way
that NFTts make money is if somebody
buys the one that you bought for more
than you bought it. So, you're just
hoping that somebody will. So, it's just
gambling, right?" I'm like, "You're
entirely correct. The whole thing is a
scam. Maybe don't buy NFTts." Um, she
later told me that her dad had been
planning to buy NFTts and she told him
and then he did not. So success.
There are some caveats I do want to
address here.
Got applause from the other room too.
Um firstly I had a rare environment uh
that I understand that I was privileged
to be in. I had small classes at most a
dozen at a private school. And while
none of these girls had prior digital
technologies experience when they
entered my class for the first time,
they were girls who were expected to do
well academically by their parents and
by the school. I was also teaching the
Cambridge curriculum and it is designed
around the students getting more time
per
year. The school that I was at spread
this time out over two years, but it
probably only needed a year and a half.
This afforded me some time to experiment
with this approach that I knew that I
could make up at the end if I needed to
do just as much revision as I had
initially thought. Luckily, I have done
some of this experimentation for you and
so you can try this out with a little
more confidence that it will work
hopefully.
Um, I also studied computer science at
university. I am a software developer by
trade and have spent many years as a
professional developer before I taught
at school. And so I have had plenty of
time to familiarize myself with a lot of
this context before I got into the
classroom. So I had to do less of that
Wikipedia research now and I did that at
university.
Lastly, I have wicked ADHD. Um, and I
absolutely live for going down a rabbit
hole and learning how a thing works.
um digging into the history or the
politics or the physics behind something
is when and where I thrive. I am told
this is not for everyone.
Um
I want to focus that while focusing on
the I want to emphasize that while
focusing on the context worked for me, I
understand it might not work for you.
Still, I would encourage you to consider
it and give it a try. I certainly saw
results with it and not just because I'm
a big softy and gave everyone great
marks even if they didn't deserve them.
Um, these students did the Cambridge
exam which is run and assessed
independently by people from Cambridge.
Um, so I have some external validation
here. I only had a single cohort that I
taught in the staff for the whole two
years of the course. So unfortunately my
sample size is low but of the seven
seven students who did that exam five of
them scored an A star which is
Cambridge's highest grade and one scored
an A. These are girls who had never had
a computer science lesson before our
classes. They'd never
elected
on a curve. So to get an A you need to
get 88 or above out of 150. These girls
scored an average of 112.8.
My supervisor said that the school had
never achieved results like this before
in computer science.
It is not a silver bullet, however. And
if a student is disengaged, no amount of
context can fix that. You might have
noticed I said I had seven students and
then I gave you six grades. The last
one, unfortunately, did not do as well
and got an E. There is only so much that
you can engage somebody who does not
wish to be engaged.
So all in all, I'd encourage you to try
it. I would love to hear how you go with
it. Thanks for coming to my talk.