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.
Remember Nicholas Steno, who determined that fossils represented parts of once-living organisms? Superposition refers to the position of rock layers and their relative ages (Figure below).
Steno also noticed that fossil seashells could be found in rocks and mountains far from any ocean. Steno proposed that if a rock contained the fossils of marine animals, the rock formed from sediments that were deposited on the seafloor. Relative age means age in comparison with other rocks, either younger or older.
Time factors of millions and billions of years is difficult even for adults to comprehend.
Fossils are important for working out the relative ages of sedimentary rocks.
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.
So, let's imagine for a second that you have a 3-layered cake. So, by definition, the oldest layer of cake would be chocolate, as it was put there first. Now all of a sudden the big tower of cookies running through the middle of your cake is the youngest feature, as the other three layers in order for it to be there.
Your 3 layers will consist of a chocolate cake, a vanilla cake, and a cheesecake, because you're crazy and your cake doesn't have to conform to standards. On your plate, you put the chocolate cake on bottom, or the first layer. Then vanilla and cheesecake are the second and third oldest, respectively. Now that I've gotten you all hungry for cake and cookies let's talk about rocks instead.