Making Fossils in Plaster
Objectives:
Students see an example of a 2:1 ratio. Students see how impressions are left in a surface the same way fossils are left in sedimentary rocks. Students can write about the procedure of the models, the results of their projects or the sequence of events.
Materials:
Focus:
The children will need the prior knowledge concerning how paleontologists find fossils and how they use these to discover how dinosaurs and other prehistoric creatures appeared. Even a slight knowledge of this can make the activity meaningful. Focus by telling the students that we will make our own "fossils".
Procedure:
First prepare a cup for each student. Have each student put their name on the cup. Have helpers pack at least a half inch of sand into the bottom of each cup. Stick one straw into the sand so that it will stand by itself, away from the edge but not in the very center of the cup. Then go outside or on a field trip and have each student collect a leaf, petals, flower or other small natural item. (Twigs don't work very well, leaves work the best.)
When returning to the classroom have each student lay their natural item flat onto the sand in their cup. Explain to the students that the plaster of Paris is mixed in a two to one ratio. This is two parts plaster to one part water. Test the students by asking if one cup of water is used, how many cups of plaster will be needed? If four cups plaster are used how much water will be needed? ect. To have a sufficient amount you will probably need at least 3 cups of plaster and 1 1/2 cups of water. You will want to mix it in small amounts since it thickens quickly.
Have the cups ready and quickly pour at least a half inch of plaster into each cup. In 24 hours you can invert the cups and rinse off the sand to reveal a "fossil" of the item the child selected. Twist the straw out and with some string the "fossil" can be made into a necklace. They can also be painted.
Close:
Ask students to write letters to their friends in other classes that explain the procedure of the project. Ask students to write down the procedure so that they can do this again over the summer in case they get bored. Put the steps of the process on cards and have the students read and arrange the sequence of steps. Have students write about what dinosaur fossils they would like to find if they were paleontologists. Ask students to explain why the plaster on top of the sand is like a sedimentary rock. Ask the students to write down things they want to remember to tell their parents tonight.
Weather | Pets | Magnets | Plants | Rocks | Colors | Dinosaurs | Experiments | Static | Oceans