Slanted Light Drills

The morning sun cut a sharp, pale rectangle across the hardwood floor near the sliding door. I set down an orange plastic bottle cap precisely at the edge of the shadow line. Using the inside curve of my right boot, I tapped it firmly forward. It glided across the polished wood, crossed the threshold of sunlight, and halted exactly against the metal door runner. I retrieved it, reset my footing two floorboards back, and repeated the strike three times until the cap followed the exact same trajectory every run.