Model building has fascinated teens for generations. But in the 21st century, tinkering with machines has reached a whole new level. This year thousands of American students – boys and girls — will participate in the world’s premiere robotics competition. High school seniors and their mentors from across the country take part in the unusual sport – one that celebrates brains rather than brawn. Ambitious teams design and build robots from scratch. Those who advance to the finals compete before 40,000 screaming fans. What their drive for success could mean for sparking innovation in American education — and defining a new cool.