What is happening right now?

Greenfoot IS Java. Its classes are provided to allow a beginner to start creating games and simulations right from the start. I believe you are correct in that the tutorial should mention how you can inspect an object in greenfoot. Right-clicking on the world and selecting Inspect on the pup-up will show all field values, not just from in MyWorld, but also from in World. The same goes for an Actor object. Inspecting an actor will show fields provided in the Actor class (namely: x, y, rotation, image and world) as well as fields you declare in its specific class. At least, your children would be able to see what fields are provided this way. Note that it is not usually a good idea to duplicate a field in a subclass.

yeah removing it fixed it

thanks