The above question is a great place to start, honestly.  It's both practical and leads to a lot of natural additional lessons.  Like, after calculating the answer, a natural question to ask is, "Yeah, but people who seek to get tested usually aren't random, right?"

SimpleStacker

I think i am like the trained doctors. But it's something I hope to rectify with my children. I try to talk to them about low level statistics frequently. Unforutnatley (fortunately?) they are getting to the point where I'm going to have to actually do some reeducation on my own part if I want to continue to impart meaningful knowledge.