Fossil
Fossils form in ways that either alter the original object or leave it intact. Unaltered remains of living plants and animals occur when they become trapped and preserved in ice, amber, desert sand or tar. Altered remains occur when forces of nature break down the original plant or animal then partially or fully replace it with mineral deposits or leave an imprint of it in the rock that eventually forms. You can teach children about this process using a number of resources.
Explanation
Explain the process of fossilization to children. A plant or animal must die in a location favorable for fossil formation in order for it to occur. In the case of unaltered fossil formation, the plant or animal must die in just the right location to find itself encased in material that preserves it. Altered fossils, those that minerals eventually replace or that leave an imprint of themselves in minerals, must die near a place where they come to rest in water. They must then remain long enough for sediment to cover and preserve them so that over many years, the weight of the sediment and seepage of minerals turns them into fossils.
Visuals
Use real fossils or resources, such as Yale University's Peabody Museum of Natural History website, educational posters and the Eyewitness series of books, to reinforce your lesson on fossils and fossil formation with visuals. The Peabody Museum and Eyewitness books offer quality photographic images of fossils. Emphasize that the formation of fossils takes millions of years, unlike the quickly formed models in the classroom project. The National Parks Service fossil department has online information and graphics showing fossil rich geology formations in several United States locations.
Create
Have children participate in gathering fossil models, such as plastic toy insects and reptiles, bones or bone models, plant material and shells. Several ways to create fossil models provide a realistic result. Remember to stress that in reality, this process takes unique conditions and millions of years. To model the formation of altered fossils, press a fossil model object covered with a thin layer of petroleum jelly into clay at the bottom of a small container. Pour plaster mixed to manufacturer's directions over it and let dry overnight. Once removed, children have a mold of their fossil in the plaster. A cast, or three-dimensional fossil, can then be made by pouring additional plaster into the mold and letting it dry. Mix sand, clay and water together, then place fossil model objects into it. Allow it to dry. Children can chisel the fossil objects out carefully with small jewelry screwdrivers. Create an unaltered model by placing a small, flat fossil model object, such as a plastic toy bug, on a piece of cardboard. Pour white glue over it and allow it to dry. Repeat as necessary to build up the layers until you cover the model. This mimics a fossil preserved in amber. Creating fossils with these methods allows children to experience the process of formation, although at a greatly enhanced speed, so that they likely understand the process better.
Tags: fossil formation, fossil model, plant animal, animal must, fossil model object, fossil models, leave imprint
