I'm an American and took the test in the US. I had the standard 2 essays, the real math section, the real verbal section, and then I got a message that I could take another math section for the chance to win $100 if I answered all of the questions correctly. Everything that I had read had indicated that test takers wouldn't know which section was unscored, but mine was clearly marked. FWIW, my real math section was MUCH more difficult than the experimental section.