The Midnight Marble Run

I stacked three thick hardcovers across the desk to build an ultimate rolling ramp! Balancing a swirling green glass marble in my hands, I hoisted it up to the highest book spine and gave it a gentle tap. Whoosh! The marble tumbled down the sloped cover, leaped cleanly over a rubber eraser, and plunged into an empty ceramic mug with a sharp clink! I threw my arms up in pure triumph, though the loud rattle in the quiet room made me freeze on the spot. What a trick!