Rock Cycle - Minerals (2B) Pre Lab
 OBJECTIVES: Observing the structure of crystals. Exploring crystal structures. VOCABULARY: amorphous crystal crystalline mineral MATERIALS: geoboard crayons Googolplex or Zometool worksheet Students use math manipulatives to explore the internal shapes of minerals. crystals of olivine
 BACKGROUND: A crystalline solid is a material with an internal atomic structure that is organized in a regular, repeating pattern. Some solids are noncrystalline which are are termed "amorphous solids." All native metals and minerals are crystalline, while glasses and plastics are amorphous. A crystal is a single piece of crystalline matter that shows the internal structure of a compound. Crystals can be composed of a wide variety of elements. They thus have a wide variety of internal structures. The concept of crystal structure is difficult for young students. It is important to emphasize that the atomic structure cannot be seen by the naked eye, but can be seen by scientists using high-powered microscopes. However, the atom structure controls what the crystal looks like, so when students look at mineral specimens, they can make accurate observations about crystal structure. PROCEDURE: If desired, construct three-dimensional counterparts to the two-dimensional structures that the students will create using the geoboard. You may wish to create pyramids, squares, diamonds, and rhombohedra.    Using the geoboard, have the students make a repeating crystalline pattern. The dots on the geoboard correspond to the internal arrangement of atoms and molecules in the crystal. By connecting the dots, the students will create analogues to crystal structures. For example, a diamond-shaped pattern would create a mineral crystal that has dipyramidal shape.    Using the worksheet, have the students create their own patterns. In mathematical terms, these patterns would be called tessellations (polygons that are repeated in a pattern.) The figure below shows a few examples of patterns that the children can make. Have students identify the shapes that they make with Googolplex or Zometool. Emphasize that the shapes are two dimensional, but that they correspond to three-dimensional structures. Compare them with the three dimensional models. You may also want to point out different two and three-dimensional shapes in the classroom.    After the students have learned to identify the shapes, have them use Googolplex to make patterns. Students can use the connectors or not, depending on their abilities. Have them place the pieces in different patterns or repeatable arrangements. The number of possible patterns is infinite. Many patterns can include more than one shape. You may want the students to draw their patterns after they assemble them. You may want to have students share their patterns with classmates. Ask them to connect the patterns with connectors before moving them. Have them try to combine patterns. This will result in more complex designs.
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