Cells, Organs and Tissues Science Quiz For Kids, Online activity for 4th, 5th And 6th Grade Kids. This is an interactive science quiz in which students will learn about the functions of some parts of a cell, the definition of organ and tissue and the role of some organs in performing specific functions in the body. This quiz is free and always online hence will serve as a science tool kit for students both at home and in school. Educators can simply watch their students practice and get automated grading.