. ♪ as i walk through my business i know i owe a debt ♪ >> john cohn's not really a rapper.s actually a computer engineer at ibm, and a somewhat wacky educator. >> i grew up liking my science and math and you will too if you follow my path -- school. >> i've never been very good at sports, and when my kids started getting older, i got snookered into volunteering in one of their classrooms, and i realized that was a great way of relating to the kids, and sort of, instead of tossing around footballs, we tossed around lightning. and so i started doing it in their schools, and then the neighborhood, and now i do it all over the country. >> john's electrifying performance is part of national lab day. president obama says it's important to encourage young people to be "makers of things, not just consumers of things." that's where a program called stem comes in. >> stem is four letters that mean -- "s" for science, "t" for technology, "e" for engineering, and "m" for math. organizations come together with the main goal of inspiring middle school and upper school children to get mor