The night before the fair, they were soldering the final connections in the school's electronics lab. It was past 8 PM. The building was silent. Leo’s sensor was working perfectly—an LED blinked green for "moisture optimal," red for "dry."

The principal was holding the solar system trophy, but the superintendent—a grizzled man in a cowboy hat—was crouched next to Leo’s sensor, watching the LED flicker from red to green as he wet a paper towel and touched it to the soil. He looked up.

"I need a partner," Leo said, his voice flat from disuse. "And the prize is five hundred dollars. I'll split it. You don't have to do any of the science."

"A home-schooler?" she said, one eyebrow raised. "You guys are like Bigfoot. People talk about you, but nobody’s ever actually seen one."