Paleontology, and in particular the study of dinosaurs, is an exciting topic to people of all ages. although most attention in today's world focuses on dinosaurs and why they became extinct, the world of paleontology includes many other interesting organisms which tell us about earth's past history. the study of fossils and the exploration of what they tell scientists about past climates and environments on earth can be an interesting study for students of all ages. teaching about earth's history is a challenge for all teachers. time factors of millions and billions of years is difficult even for adults to comprehend. however, "relative" dating or time can be an easy concept for students to learn. in this activity, students begin a sequencing activity with familiar items — letters written on cards. once they are able to manipulate the cards into the correct sequence, they are asked to do a similar sequencing activity using fossil pictures printed on "rock layer" cards. sequencing the rock layers will show students how paleontologists use fossils to give relative dates to rock strata. once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of earth's history. these major concepts are part of the denver earth science project's "paleontology and dinosaurs" module written for students in grades 7-10. the module is an integrated unit which addresses the following national science education standards: *science as inquiry: students develop the abilities necessary to do scientific inquiry — identify questions, design and conduct scientific investigations, use appropriate tools and technologies to gather, analyze and interpret data, think critically and logically to make the relationships between evidence and explanations, communicate results, and use mathematics in all aspects of scientific inquiry. *life science: fossils indicate that many organisms that lived long ago are extinct. extinction of species is common; most of the species that have lived on the earth no longer exist. *earth and space science: fossils provide important evidence of how life and environmental conditions have changed. the complete "paleontology and dinosaurs" module takes approximately four week.