"This is awesome," crows Bell. "Okay, so..." She picks up a stick and plants it in the ground, then runs to a distant point still visible from the original. Then she picks a spot between the two to stand so she can see each stick. "I'll time you, and you can start with the small stuff and move it as fast as you can from the first stick to the second stick! And then try the bigger stuff and we'll see if that's slower. Or it could be faster!"