
Big Boy, a cement mixer truck, shows viewers how concrete is made and what it is used for. The cement yard receives a load of sand from Red, a Mack hopper semi-truck, and a load of gravel from Blue, a Western Star hopper semi-truck who dump their loads into grates, the gravel is taken by a conveyor belt and the different sizes of gravel are sorted into piles. Sally, a Caterpillar front-end loader, keeps the gravel piles in the yard tidy. Big Boy is loaded with concrete and takes his load to replace a road while Tiny, also a cement mixer, takes his load of concrete to a skyscraper under construction.