This looks like a great idea with a lot of hard work ahead of you.<p>You mention a few different areas it could work in (education, enterprise, consumers), but really you need to pick one and really focus on it - you will dissipate your focus and energies if you try to serve even two of these markets at the same time. Might be worth picking something far away from languages since Duo and other apps have that sewn up already. It would be hard to compete.<p>I like the education/school idea but you'd have to make the product free and focus on curricula and really serving those well. Perhaps target it at teachers and make it easier for them to construct lessons.<p>Need to make sure it targets the device that your markets will be using, which probably means phones rather than desktop or ipad.<p>Feedback:
1. Password requirements are a little annoying, perhaps loosen those a bit.
2. First examples are way too broad - pick an area, focus and try to execute just for that area, so that people see immediately what it is for (e.g. make your lessons as a teacher) and you have a target customer you can go after.
3. Your examples need a <i>lot</i> more work and polish, I did the launch to moon base alpha - the pictures don't add anything IMO, and I didn't feel like I really learned much because the questions were too fuzzy and the answers were not informative, you need to build in a better feedback loop and probably pick examples which are <i>far</i> more clearcut.
4. There is some very weird/wrong content IMO e.g. use a 'gravitational slingshot' instead of burning fuel - the vast majority of spacecraft burn fuel to change course, including the rare cases where they use a gravitational slingshot.
5. Content is king - I get this is supposed to be some quick examples you threw together but you need to step back and consider what impression this gives of your product - it makes the whole thing seems slipshod and ill-thought out. You need some real, very well thought out content here to make it seem worthwhile. The user should feel like they learning something in your examples.<p>So it looks like you have the basics here for your goal, but you need to focus on content and make sure you provide good feedback when the user gives a wrong answer as this is the biggest point of friction when learning. Also consider how someone like a teacher would give this to kids and how the kids would react to it - I'd recommend trying to connect with a teacher and get their honest feedback, that sounds like a promising direction even if initially they'll tell you it'll never work, they might give you some good pointers.