The Digestive System Quiz Online, 4th & 5th Grade, A science quiz for students to label the parts of the digestive system. This is an interactive science test online that featuring a diagram of the digestive track which students have to label with parts like the mouth, esophagus, stomach, large intestine, rectum, small intestine, anus and more. Each section of the digestive system plays a specific role in the breakdown of food into smaller units that can be absorbed by the body. A good way to start understanding the process is to be able to draw and annotate a diagram of the digestive system.