1
00:00:00,000 --> 00:00:02,840
One of the most important concepts of computer science,

2
00:00:02,840 --> 00:00:07,230
is how to define new commands;
how to add your own words to the computer language.

3
00:00:08,571 --> 00:00:13,072
Most computer languages have only about a hundred words or commands

4
00:00:13,072 --> 00:00:18,252
and the art is to define your own new words out of these coding blocks.

5
00:00:18,252 --> 00:00:20,200
We do this all the time at sports.

6
00:00:21,922 --> 00:00:26,930
In basketball you learn how to dribble, how to do a lay-up and how to rebound.

7
00:00:26,930 --> 00:00:30,911
Once you've learned these moves,
you learn new moves

8
00:00:30,911 --> 00:00:34,714
and put together these building blocks, 
like a pick and roll or give and go

9
00:00:34,714 --> 00:00:37,503
and from there you can do more complex plays.

10
00:00:37,503 --> 00:00:43,201
Once you learned that play and give it a name,
everybody on the team knows how to do it.

11
00:00:43,201 --> 00:00:47,344
Simulary, once you learned a computer how to do an action once,

12
00:00:47,344 --> 00:00:49,086
using these sequence of commands,

13
00:00:49,086 --> 00:00:53,721
you can make up your own name for that action,
so it's easier to repeat it later.

14
00:00:53,721 --> 00:00:58,273
When you define your own command and give it a name,
it's called a function.

15
00:00:59,613 --> 00:01:00,868
If you are programming with blocks,

16
00:01:00,868 --> 00:01:05,355
you can use functions if there is a set of actions
which you are gonna use a lot of times.

17
00:01:05,355 --> 00:01:09,177
For example, you've written code to create a square,

18
00:01:09,177 --> 00:01:13,344
You could define this as a function called "create a square".

19
00:01:13,344 --> 00:01:18,926
Now you have a new block 
that you can use multiple times to create multiple squares.

20
00:01:19,816 --> 00:01:23,353
A lot of simple functions can be used,
to create more complex patterns.

21
00:01:24,073 --> 00:01:25,519
In the next puzzle,

22
00:01:25,519 --> 00:01:28,112
the code you recently wrote to make a circle

23
00:01:28,112 --> 00:01:31,842
is available to you as a new function
that can make circles of different sizes.

24
00:01:31,842 --> 00:01:36,309
Can you use it to help Elsa to create a new beautiful pattern in the snow?