If you can do that and convince thousands parents to use your software, hopefully gaining a bit of notice, then you'll be in postion to say to Microsoft, "I've got a way I can help you make a bit more money.".
If you're still not discouraged, and still want to create learning software for the XBox 360 then I suggest you start by creating PC software first. These are the devices the parents have shown, by voting with their pocket books, that they want to use to educate their children, not consoles like the XBox 360. Educational software for children is now mostly the domain of specialized electronic devices, like those offered by LeapFrog and VTech. Even on the PC where it used have a significant market, that market has shrunk to a fraction of what it used to be. I don't know if any of this is really on topic for this forum, but just to try to discourage you further, I'd like to point out the educational software has been pretty much a failure on the consoles. Microsoft is not a charity and cannot recieve any donations from the foundation to do this. It could, in theory at least, be donated to a charity making educational content for the XBox 360, but the content would still have to be sold commercially since Microsoft still wants its cut.
Can't some of that money be used to add a LMS to XBox Live and develop compelling educational content, with "Achievements" in academic subjects? There was a recent announcement that Warren Buffet will donate >$30B to the Bill and Melinda Gates Foundation, and that the second priority of that foundation is US Education.