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

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

a stopping value, and our interval.

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

the same number of steps forward as our interval
value.

We stop circling when we get to our stopping value.

The person with the highest
score wins!

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

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

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

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

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

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

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

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

the power grid is balanced, your lights stay on,

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

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

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

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

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

and a longitude. We have to calculate the physics,

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

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

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

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

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

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

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

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