I second the vote for Tesla. I’d also add Percy Julian!

This sounds like a terrific history project. Best of luck to you!

George Washington Carver (if you don’t mention peanut butter nobody will ever get it) He is the father of modern synthetics (what would our nation be without them?) and the savior of an entire regional economy, an internationally honored artist, a concert pianist, a hard-working humanitarian, and personal friend of Ghandi, Henry Ford, Henry A. Wallace, Booker T. Washington and numerous other famous figures. Truly an American Hero (and nobody knows him for anything but inventing peanut butter, which he didn’t actually do) His story is amazing, and all of these achievments will give you lots of material to work with and nobody will ever guess him.

Nikola Tesla?

http://inventors.about.com/od/tstartinventions/a/Nikola_Tesla.htm

http://en.wikipedia.org/wiki/Nikola_Tesla

http://www.tesla-museum.org/

http://www.pbs.org/tesla/