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My name is Jens Bergensten, but I'm better known as Jeb. I'm the lead developer on Minecraft

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here at mojang.com. I think I was 11 or maybe 12 and I started programming because I wanted

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to make games. One of my father's friends told me that in order to make games you need

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to learn how to program. So that's how I got started. I like designing and figuring out

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the architecture of things. That's what I really like about Minecraft. Over the next

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hour you're going to learn the basics of computer science by programming Alex or Steve to move

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through a simulated piece of a Minecraft world. Traditional programming is usually in text,

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but today we'll use blockly: a system which uses blocks that you can drag and drop to

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write programs. Under the hood, you're creating JavaScript code. The concepts that you'll

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be learning are what computer programmers use everyday and are the foundation to computer

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science. Here at Mojang we use these same concepts to make Minecraft work. Before you

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start, you'll pick your character. I'm going to choose Alex. Let's build code for a program

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that will help her move around the screen. Your screen is split into three main parts.

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On the left is the Minecraft play space, where your program will run. The instructions for

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each level are written below. This middle area is the toolbox and each of these blocks

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is a command that directs Alex's actions. The white space on the right is called the

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work space and this is where we'll build our program. If we drag the \"move forward\" block

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to our workspace and then click Run, what happens? Alex moves forward one space on the

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grid. And what if we wanted to do something after she moves forward one space? We can

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add another block to our program. I'm going to choose the \"turn right\"; block, and I'll drag

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it underneath my \"move forward\" block until this orange line appears. Then, I'll drop

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it and the two blocks will snap together. When we press Run again, Alex will perform

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the commands that are stacked from top to bottom in our workspace. And if you ever want

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to delete a block, just drag it from the stack back to the toolbox. To undo your changes

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and to get back to how the level started, use the Start Over button in the top right

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corner of the workspace. One more thing, you see the little triangle on the turn blocks?

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Anytime you see these triangles, it means that you can pick a different option. Let's

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start coding!