Farid and the Bell Machine

On Saturday morning, the school gym smelled of floor wax and nervous excitement. Farid had forty minutes before the doors opened for the science fair, and one very important thing to finish: his Seven-Step Machine. A marble would roll down a ramp of cardboard tubes, topple a row of dominoes, send a toy wagon trundling along a plank and, seven steps later, ring a small bicycle bell. He had been building it for three weeks.

His little sister Dina sat on a stool beside the table, swinging her feet. She pointed at one of the table legs. “The table wobbles. Look at it.”

Farid did not look. “Tables don’t wobble. Ramps wobble. Please don’t touch anything.” Dina folded her arms and studied the ceiling as if it were far more interesting than her brother.