It depends how much are you able to use it. You may show only the problems that you want to show :D. Honestly I do not know how much elementary school kids would be able to use this game because it is complicated, for instance you have to consider how t build a rocket (however there are some stock available models) antenna connections, signal delay, charge of batteries, drag and dynamics (pic)
and so on but surely it is a nice tool to make them curious about astronomy. Especially if they see you play it just because you know certain things that they don't... probably they would know these things too. There are a lot of video tutorials on web, check them. However you may also use cheats to make it easier. I can suggest you also two other software for your astronomy class: Universe Sandbox (29$) and Space engine (free)
RE: How to reach the orbit: the very basics