In college I took a single credit Scratch class where we'd go out in the community and teach an after-school lesson for about an hour once a week to 4th and 5th graders. Honestly, it was one of the best parts of my semester. Seeing them grow and explore was fantastic.

In line with the hacker ethic, we decompiled Minecraft as a demo and started playing around with the jump math with them. It instantly clicked, based on their experience moving Scratch characters, what the changes we were doing were going to do before we ran it. That's a powerful link, even if they didn't realize that "jumping to the clouds" still causes fall damage (Which was subsequently turned off in the code).