Which part of a tractor-trailer is the tractor, and which is the trailer? What kinds of things to do these trucks carry? Young readers discover the answers to these questions and many more as they learn about these huge trucks. Tractor-trailers are familiar vehicles, and young readers will learn new information about them with every turn of the page. a picture glossary is included to aid readers in expanding their vocabulary, and strong picture-text correlation on each page helps develop comprehension skills. Simple, accessible text is paired with colorful images of tractor-trailers on the road.