Interactive Movable Parts Book. Five construction trucks are hard at work-what are they building? Find out as you move each truck along its track. Kids will love exploring the construction site with a bulldozer, dump truck, and other heavy equipment while learning what each machine does. Storytime is sure to be filled with a variety of beeps, booms, and crashes as kids imagine the busy trucks doing their jobs. On opening day a surprise pop-up is a great reward for all of their hard work!