Interesting stuff, thanks for sharing!

I worked on a similar project where they wanted to teach kids how to save. Definitely stressed me out because I didn't know the first thing about designing for kids either. One of the challenges I had were really nailing down the age range we wanted to target—someone who's 12-16 years old won't learn or find things engaging the same way that 5-8 year old kids would, so to say that a persona of 5-16 years might be too broad.

• Things like material design are aesthetically pleasing for us, but that doesn't necessarily mean that it's engaging for them. Same with immersive audio; we're not interested in hearing sounds every time we click/tap a button, but kids enjoy it (and it helps them with cognitive understanding).

I found this after finishing my project (naturally): http://www.bbc.co.uk/gel/guidelines/how-to-design-for-children

Maybe you'll get a kick out of it.