They need to consider how much energy is required to get there - will they need a spaceship and what are the effects of gravity?
Think of their own questions about going to the moon.
What shape is the moon and how big is it?
They need to think in terms of three dimensional position and these questions stimulate this spatial awareness. It would help if they have an understanding of measurements - particularly length. They should also know about shapes - particularly 3D shapes.
Of course they may want to go somewhere closer at hand - try to make that involve travelling in three dimensions.
All training apps are subject to Apple's standard licensing agreement. Copyright is protected for Alexander Watt 2011/ 2012/ 2013/ 2014/ 2015/ 2016. Feedback is welcomed in terms of adding functionality to downloaded apps. Apple, iPod, iPhone, iTunes, iPod touch are registered trademarks of Apple Computer, Inc. If you find links you find inappropriate please email me at firstname.lastname@example.org and I will check it. I have provided these links with the best intentions however I cannot be held responsible for their content.