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One of the most important concepts in computer[br]science is how to define new commands, how

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to add your own words to a computer language.[br]Most computer languages have only about one

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hundred words or commands. The art and magic[br]is in defining your own new words out of these

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building blocks. We do this all the time in[br]sports. For example, in basketball, you start

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by learning how to dribble, how to do a lay-up,[br]how to rebound. Once you've learned these

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really basic moves, you learn new moves and[br]put together these building blocks, like a

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pick and roll or give and go. You can then[br]go from there to do more complex plays. Once

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you learn that play and give it a name, everybody[br]on the team knows how to do it. Similarly

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once you've taught a computer how to do an[br]action once using these sequences of commands,

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you can make up your own name for that action[br]so it's easy to repeat it later. When you

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define your own command and give it a name,[br]that's called a function. Now we're going

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to use functions to help the bee. In this[br]example, our function is called get 2 nectar,

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this green block right here. We know what[br]get 2 nectar does by looking at this grey

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box which is the function definition. If we[br]look inside there, the get 2 nectar is going

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to get nectar and then get nectar again. Always[br]look at what's inside the grey box so that

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you know what these green function blocks[br]can do.