Apologies, disclaimer, I work with kids. I'm not saying all of them don't know it. Just as there are 9 year old developers, I'm sure there are plenty of kids who know about SD cards. What I was talking about was the general population though.

To put it in perspective the first iPhone came out in 2007. A 15 year old now was 6 at that time; that's first grade. iPads came out in 2010. They were 9, fourth grade.