Of course, Tally had to learn too. Shay kept saying that if your feet weren't in the right place, the smartest board in the world couldn't keep you on. The riding surface was all knobbly for traction, but it was amazing how easy it was to slip off.

The board was oval-shaped, about half as long as Tally was tall, and black with the silver spots of a cheetah-the only animal in the world that could run faster than a hoverboard could fly. It was Shay's first board, and she'd never recycled it. Until today, it had hung on the wall above her bed.

Tally snapped her fingers, bent her knees as she rose into the air, then leaned forward to pick up speed.

Shay cruised along just above her, staying a little behind.

The trees started to rush by, whipping Tally's arms with the sharp stings of evergreen needles. The board wouldn't let her crash into anything solid, but it didn't get too concerned about twigs.

"Extend your arms. Keep your feet apart!" Shay yelled for the thousandth time. Tally nervously scooted her left foot forward.

At the end of the park, Tally leaned to her right, and the board pulled into a long, steep turn. She bent her knees, growing heavy as she cut back toward where they'd started.

Now Tally was rushing toward the slalom flags, crouching as she drew closer. She could feel the wind drying her lips, lifting her ponytail up.

"Oh, boy," she whispered.

The board raced past the first flag, and she leaned hard right, her arms all the way out now for balance.

"Switch!" cried Shay. Tally twisted her body to bring the board under her and across, cutting around the next flag. Once it was past, she twisted again.