Meaning: The children are moving quickly by putting one foot in front of the other, and their feet are hitting the ground hard and repeatedly.
Choice of Words: The verb "run" means to move quickly by putting one foot in front of the other. "Feet" are the part of the body that you walk or stand on. "Pounding" means to hit something hard and repeatedly. "Pavement" is the hard surface of a road or sidewalk.