BACKGROUND:
People, young and old, like to feel shiny, smooth rocks. Many do not even
realize that these types of rocks have endured erosion, possibly as the
rocks tossed and turned down a river's path. Abrasion by glaciers and wind
also results in a smooth surface on a rock.
Throughout history, civilizations have used rocks and minerals in
sacred ceremonies. People even have spent money to purchase "pet
rocks." Rocks and minerals have characteristics that lure people to
them, including their strength, their smoothness, and their beauty.
Rocks and minerals can become the storyteller’s "liar stone."
The rock or mineral can neither confirm nor deny the tale. This is what
makes just one rock, a perfect way for students to communicate.
PROCEDURE:
- Instruct students to look on the Internet for information that show a
"fun" way to present rocks. The following web sites on sand
castles can help students realize that people around the world can enjoy
sand without knowing all the science behind them. However, knowing the
science makes it more interesting.
www.sandcastlecentral.com/tips/index.html
Sand castles for beginners gives information on how to build an award
winning sand castle.
- Instruct the students to study the worksheet and use their imagination
to decide how Billy can determine why the rocks became round. Some
students may want to be more scientific, but others may want to develop
a fictional story line. The story below is an example. Remind students
that "Billy" could refer to a boy, girl, or even a goat.
Billy found pebbles that were along a river. The river's waters
carried the rocks along the bottom of the river bed. The pebbles were
eroded by abrasion. The longer a pebble stays in the river bed, the more
rounded it will become. The more angular a pebble is, reflects that it
has not been moving for very long. Billy found the two different types
of rocks together (one very old, eroded and well rounded, the other very
angular and new) because the river can erode new rock anywhere on its
journey.
