D - Secure the Planet!

Make sure your robot is setup in the same way as the previous sections!

You don't need the magnet module for this section.

For the rest of this lesson, we need to be able to make the robot turn accurately.

Build the program in the picture, and try it out on the robot - it should turn a small amount, then stop.

For the next few steps, we need to make out robot turn exactly 90 degrees - adjust the length of the pause block until your robot accurately turns 90 degrees.

You won't be able to complete the next steps until your robot turns accurately - get your teacher to check before you move on!

Now you can turn by 90 degrees, write a program that makes your robot move in a square!

It should like something like the example in the picture, but your 'pause' blocks will be different.

If you think about it, you only need to reverse 1 motor and then set it to forwards again to change direction - one motor can be going forward all the time.

Also, you don't necessarily need to stop after turning - just set the motor going in reverse to go forward again!

Making that last program took a while - and the robot was just doing the same things over and over again.

Say we wanted to drive in a square 10 times - that would take ages to program!

Driving in a square was doing the same thing 4 times:

Drive forward

Pause

Turn

Pause

We can use a loop to get the computer to repeat these steps for us!

One of the most useful loops is the forever loop - we have this block in every program, next to the 'on start' block - we just haven't used it yet!

Anything inside this loop is just repeated forever.

Let's use this to make our robot move in a square forever.

Move some blocks into the forever block, to make the robot drive forwards, then turn 90 degrees, like in the picture.

Delete the rest of the code in the on start block by dragging it into the left menu - we don't need this anymore.

Upload the code to your robot - it should move in a square forever!

What if we don't want to move in a square forever?

Luckily, there are other types of loops we can use that can loop things in different ways.

Click on the Loops menu, and drag in a repeat 4 times loop. This block will repeat any code inside it, but only the number of times that you tell it to!

Put the new loop block into the on start block, and move the other code from the forever loop into the new repeat 4 times loop, like the picture.

Now your robot should move in a square once, then stop!

Now your robot can drive in a square using a loop, let's change the code so it will drive in a figure of 8.

Have a look at the picture if you don't know what a figure of 8 is.

Try to split the shape up into 2 sections, and use a do _ times loop to reduce the length of your sequence.