# CS Unplugged – Sorting networks (sample classroom lesson)

[Sorting Networks] So we’ve come outside today
to learn a little bit more about how computers work, and what we have is, this is like a
supercomputer made out of chalk. And I’m gonna show you why in a moment,
I need six volunteers. Awesome. What I’m gonna do is I’m gonna give you a
disk, and you need to go and stand on the circles – the far far away ones. So Rhylee you go away over
in that far away one. Robert you go into the next one. Ellie you go over to that next one. Kourosh can you go over there. Lewis can you go into the last one. Okay! So I’ve got you guys here and this is all
about teamwork. And it’s all about organising data. So you guys are the start of the data you’re
coming in and you’re all out of order, we’ve got the number 5, number 2, number 1,
number 3, number 6 and number 4. And so before we start going into the supercomputer,
all I need to teach you is this symbol here. What does this symbol here mean? What does it mean Lewis? Smaller then bigger. Smaller then bigger what’s some more mathematical
terms that we could use for smaller and bigger — yep?
— Less than or greater than Less than or greater than. Awesome, so what
we have is the orange line is the less than, and the blue line is the greater than. So let’s see how this works. Can you all
take a step into the box. Can you say hi to the person next to you and
give them a big smile. Not too cheesy. Now what you need to do is decide: have I
got the bigger number or have I got the smaller number. And then the bigger number
follows the blue line, the smaller number follows the orange line, go. Now, you need to look around and check everyone’s
there and then you need to say hi and give the person a big smile go. Now decide who’s got the smaller, who’s got
the greater number. Do you guys know what to do? Do the next one I didn’t see anyone smiling
and saying hello, smile and say hello. Hi. Now make your decision go. Hello! Nice. What number do you have? I have 4 so I’ll go this way. Perfect. Cool so I’m gonna get you guys to turn and
face me this way and we’re gonna see what happened to our numbers, can you turn and
hold up your numbers please? Oh, wow Kourosh what number have you got? — One.
— What number have you got Lewis? Two. Three. Four. Five. Six. Okay what just happened to our numbers? We put them into our supercomputer that’s
chalk that’s like a supercomputer, and we processed it and what happened? We came back in the right order. Oh, do you think that would work with everything?
[Tip: This activity can be used to sort anything!] Yes.
[Tip: This activity can be used to sort anything!] What kind of things
could we sort in order do you think? — Yep?
— Books. We could sort books, what else? Letters? Yes, what else? Bells? Yes, what else? Notes. Yes, what else? What about big numbers? Really big numbers could we do that? — Yes.
— Yep, cool. [Book titles (alphabetical)] [Large Numbers (numeric order)] [Letters (alphabetical)] [Handbells (musical pitch, higher or lower)] Which one sounds lower and which one’s higher? I’m lower. You’re lower, sweet. Okay, let’s sound one at a time. Yep. Which one sounds lower? This one’s lower. Yep, let’s try play it once more to make sure. That’s sounds good. Let’s hear it, let’s hear it one more time. Yep. Okay, keep going.