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This lesson is called For Loop Fun. In this[br]lesson, we'll use a number line to play a dice game.

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Each player will roll three times[br]to assign a starting value,

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a stopping value, and our interval.

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During each turn, we circle[br]our starting value, and every value that is

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the same number of steps forward as our interval[br]value.

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We stop circling when we get to our stopping value.

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The person with the highest[br]score wins!

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For loops can come in handy in a lot of places.

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If you were a[br]meteorologist, you would use for loops all the time.

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Hi, I'm Becky. I work at Able Driller[br]Renewables as a wind meteorologist.

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I forecast wind speeds for the Columbia River Gorge area, where the company owns wind farms.

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We're trying to understand how much wind is going to be there,

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so that we know how much power is going to be outputted.

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We give that information to real time energy traders. They buy and sell power,

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based on how much power we tell[br]them is going to be there, in order to make sure

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the power grid is balanced, your lights stay on,

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and that we maximize energy we get out of our wind farms.

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We're at the national control center for Eber Troller Renewables here in Portland,

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and this is where we have information coming in from all our farms across the country.

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Even the highest power computers[br]today can't simulate the atmosphere everywhere.

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In computer forecasting models, we have what[br]we call a grid. Each grid point is a latitude,

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and a longitude. We have to calculate the physics,

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and try to figure out wind speeds, temperature, pressure, that sort of thing.

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Since these are fairly big grids and we're doing this in a lot of points,

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we're looping over these[br]things millions and millions of times.

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Everything I do, I'll use for loops. Here for example[br]is a for loop right there.

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When you're forecasting wind, there's so many different parameters that go into it,

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that go into it it would be impossible for a human to sit down and do all those calculations.

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There's so many different aspects to what's going to be affecting the wind

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that we need a computer model in order to forecast it.