Educator Handbook: Casts and Molds
CASTS AND MOLDS
GRADE LEVEL: K - 3
OBJECTIVE:
Students will be able to explain the difference between casts and molds of fossils.
MATERIALS:
Play dough or modeling clay, one piece per student
Rocks containing fossils and impressions of fossils.
PROCEDURE:
1. Distribute one piece of clay and one fossil rock to each student.
2. Have the students find fossils in or on the rocks and cover them with the clay to make an impression. When they remove the clay they will have either a cast or a mold of the fossil.
3. Explain the difference between casts and molds. A fossil cast is the shape of the fossil sticking out of the fossil rock. If there is a depression where a fossil was set in the rock this is a mold. (To remember the difference, think of the Jello mold - you pour the Jello into the mold.) The clay will produce the opposite configuration. It will make a cast from a mold and a mold from a cast. Students will probably have at least one of each.
Internal cast Internal mold, lined with quartz The Devonian snail Paleozygopleura hamiltonae
4. Describe the different types of fossils to the students: clams, snails, corals, sponges, and crinoids. Ask the students if they know what the animals looked like when they were alive. Have students draw pictures of their ideas. EXTENSIONS/EVALUATIONS: 5. Have the students identify the fossils in the diorama at the Falls Interpretive Center. Have them compare their pictures to the scientist's conception. 6. Have students identify casts and molds on the fossil beds. Have them bring along some clay and make a cast or mold of something they haven't seen before.
Created January 25, 2010 |
