Greenfoot or BlueJ

I believe that Greenfoot (the application) is built on top of BlueJ, so yeah; for starters, Greenfoot would probably be the place to start. I would say that making use of the Java tutorials would provide a firm foundation. The second section of the left labeled in red, called 'Trails Covering the Basics' is a great starting-point. It would be best to at least get started there before starting in Greenfoot itself, which also has tutorials (mostly for using Greenfoot -- not for programming in Java). If anybody has any better suggestions, please chime in; thanks.

Essentially, BlueJ is a simple Java programming environment, and Greenfoot builds on that by providing a graphics/simulation API and tailors the environment to that. For kids aged 13-15 in particular the benefit of Greenfoot over BlueJ is that they can do more interesting things with it much sooner. The transition from Greenfoot to BlueJ is very straightforward so I personally wouldn't be too concerned about the fact that they will use BlueJ in school.

Speaking from experience, I would advice to start with Greenfoot. I agree with davmac: you can make fun things faster and earlier than with BlueJ. And personally, I enjoyed to look at BlueJ after I learned Greenfoot, just because I liked to look at more 'basic java', if you get what I mean :)

i would also say to start with greenfoot, as they would be able to see changes in simple games a lot sooner on there. i agree with all the above posters. (i gained more out of taking my software engineering class using greenfoot than i did with some of my java classes using just a programming environment the teacher at this school created.)

Thank you all, I think I will start them with Greenfoot, and run them through the exercises in the book (have to buy the book first). This should get them started, and potentially mostly on their own while off for the summer and when I am at work.