Hour of Code

Hour of CodePower

Computers are…

• Powerful

• Useful

• Amazing

• Everywhere

• Clever?

Computers are…

• Just a big pile of wires and chips put together in a clever way

• (not those chips; silicon chips)

• They seem useful and clever because they can follow our instructions really well.

Great things computers do

• What are your favourite uses of computers?

Great things computers do• Communication: email, messaging, phone calls

• Entertainment: making movies, showing movies, playing games

• Analysing information: weather forecasts, speech recognition, web search

• Controlling other things: aeroplanes, washing machines, … just about everything.

Paddington isn’t really thereHe was drawn by a computer

But they’re not clever• All a computer can do is follow instructions.

• Everything that any computer ever does, it was told to do by somebody.

• Computers carry out 10,000,000,000,000,000,000 instructions every second! That is roughly one billion per person.

• The instructions are programs written in a programming language, also called code.

Code• Code used to look like

this: carefully punched holes on cards !

• These days it is much easier to read and write.

An old code

• The Roman general Julius Caesar used a code to make his messages secret.

• He moved every letter of the message three places on in the alphabet.

W i d c o m b eZ l g f r p e h

An old code, in code

Code: four easy ideas• There are really only four kinds of things to

understand:

• moving information: getting it from somewhere, or putting it somewhere

• calculating with information

• choosing what to do next

• repeating some instructions over and over again

Repetition: the big idea

• Repetition is the reason computers are so useful.

• We have to write every instruction, but we don’t have time to write 10,000,000,000,000,000,000 instructions per second!

• So we write a few and ask the computer to repeat them over and over again.

Repetition• Dear computer, here is a big list of pictures. Please

do this:

1. find the first picture you haven’t dealt with yet

2. draw the picture on my screen

3. mark that picture as done

4. go back to step 1 and get the next picture.

Repetition in Scratch

Every way of coding has some way of telling the computer to repeat instructions.

Keep going until something special

happens

Keep going until someone turns

the computer off

Where’s the cleverness?

• The cleverness comes from moving data, calculating, choosing what to do, and repeating in interesting ways.

• Those interesting ideas come from people.

• Why not you?

Learn about coding• By learning a little bit about coding, you can:

• understand a bit better all the amazing things that computers are doing

• maybe, create the next great game, or an amazing movie effect, or… something nobody has thought of yet.

• It will take more than an hour!

Start here. Go… where?• The Hour of Code is your start with coding.

• You also learn Computing throughout school.

• You can learn programming at school, at university, or at home.

• It is about simple ideas, used creatively, to do great things.

• What will you do?