## Lesson 1: Lines and Shapes

Open NetLogo and select the `Interface` tab. Select the textbox at the bottom of the `Command Center` to input commands. The two sections are highlighted in red.

This is how you make a turtle:

``````create-turtles 1
``````

We are going to ask our turtles to draw underneath them as they move.

``````ask turtles [ pendown ]
``````

We can also ask the turtles to change their shape or size.

``````ask turtles [ set size 5 ]
ask turtles [ set shape "square" ]
ask turtles [ set shape "bug" ]
``````

To see a list of shapes, you can run `show shapes`

Let's see what we have so far:

Now let's ask the turtle to move forward `5 steps` and then turn right `60` degrees. I hope you guys remember your shapes. It's especially useful if you remember how big the angles of the shape are.

``````ask turtles [ forward 5 ]
ask turtles [ right 60 ]
``````

Your turtle should look like this:

We can combine the 2 instructions to one line as follows.

``````ask turtles [ forward 5 right 60 ]
``````

Alright, why don't we tell this turtle to repeat the last instruction 3 more times?

``````ask turtles [repeat 3 [forward 5 right 60 ] ]
``````

Why don't we look at what we have so far?

It looks like we almost have a shape. What shape does this look like? Why don't we complete the shape? What instructions do we need to give to complete the shape?

Note: if you make a mistake by giving the wrong instruction to the turtle, you can reset and start again by running:

``````clear-all
``````

We can even keep telling the turtles to repeat what they're repeating. Something like:

``````clear-all
create-turtles 1
ask turtles [ repeat 6 [repeat 6 [ forward 5 right 60] right 60 ] ]
``````

You should get something like this.

Very pretty, isn't it?

### We can also make it faster. This is useful later when we have very slow animations.

We can also tell the turtle to move backwards and to the left.

``````ask turtles [ left 60 ]
ask turtles [ back 4 ]
``````

Okay, now let's clean up that mess we drew. This time we will create 2 turtles.

``````clear-all
create-turtles 2
``````

Do you notice where the 2 turtles are? They are right on top of each other. Why don't we ask them to move?

``````ask turtles [ pendown ]
ask turtles [ forward 5 ]
ask turtles [ right 180 ]
``````

But what if we don't want them on top of each other? Okay, let's try this again:

``````clear-all
create-turtles 2 [setxy random-xcor random-ycor ]
``````

Where are the turtles? Try running that command again.

``````clear-all
create-turtles 2 [setxy random-xcor random-ycor ]
``````

Okay, now we made our turtles, let's tell them to move exactly like before.

``````ask turtles [ pendown ]
ask turtles [ forward 5 ]
ask turtles [ right 60 ]
ask turtles repeat 5 [ forward 5 right 60 ]
``````

So what's happening? We're giving all the turtles the same set of instructions. So in this case, both turtles are moving, even though they are in different places. Why don't you try the above code for 3 turtles? Or 5 turtles? Or more?

``````clear-all
create-turtles 10 [setxy random-xcor random-ycor ]
ask turtles [ forward 5 ]
ask turtles [ right 60 ]
ask turtles repeat 5 [ forward 5 right 60 ]
``````