Label The Heart Diagram Quiz Online. This is a biology quiz for children in 2nd, 3rd, 4th, 5th and 6th grades. This is an interactive online test which students can use to learn the different parts of a the heart and possibly their functions. The activity can be taken directly on the computer or on a mobile tablet. For more practice, print out the worksheet on heart anatomy below >>>. This resource is for parents and teachers of science.