Select the constant controller at bottom left and change the value of the constant, a, and observe the transformations. Also if you select OPTIONS and choose animation up/down and set values say -360 to 360, steps of 5, click ok and press play. Furthermore, use the left mouse to move the centre (origin) and observe. Note: Positive 30 means anticlockwise rotation, -90 means clockwise.

If you make any errors, start again! You can use the pen in class discussions.
You may need to download Autograph Player (Link at bottom of this page).