Strictly spoken it's a piece of software, simulating the Solar System's bodies in 3D on your Windows or Linux PC (will work in most *NIX's as well). In difference to quite a few other programs it does so in realtime. Meaning you can view all the planets, moons and spaceships move along their paths, trace them, follow them, orbit them and even control them (time and spaceship contol). And you won't have to fight your way through hordes of green, slimey and one-eyed aliens for that ;-)
This study guide should provide you with a solid foundation for creating your own models. It is designed to be done in conjunction with Learning Lab 6, which provides a detailed lab for starting with an idea and ending up with a completed original model, although if you are new to NetLogo, you are probably better offer completing the earlier Learning Labs first as Lab 6 is more advanced.
The NetLogo User’s Manual provides a lot of good resources for learning NetLogo. These tutorials build upon many of them, drawing from the Programming Guide, and expanding on important concepts.
Software for constructing and reflecting on diagrams of one's ideas
Belvedere 4.1 is designed to help support problem-based collaborative learning scenarios with concept and evidence moodels, and provides multiple representational views (tables and graphs) on those models.
Belvedere was originally intended to help secondary school students learn critical inquiry skills that they can apply in everyday life as well as in science, but can be adopted to other applications as well.
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S. Abiteboul, O. Greenshpan, and T. Milo. WIDM '08: Proceeding of the 10th ACM workshop on Web information and data management, page 87-94. New York, NY, USA, ACM, (2008)
S. Ajitha, T. Kumar, D. Geetha, and K. Kanth. 2010 International Conference on Industrial and Information Systems (ICIIS), page 372--376. IEEE, (August 2010)