BACKGROUND:
Sand is a natural component of oceans, rivers, or lakes because the rocks
surrounding them have been eroded. Erosion occurs when wind, rain, and ice
crash onto a rock and break it into smaller pieces. Within a certain size
range, these little pieces of rock are called "sand." If the
pieces are bigger than sand, you can call them gravel or pebbles.
Sand takes on the "look" of the rocks that it came. If the rock
is granite, the sand will have white, yellow, and a small amount of dark
minerals eroded from the granite. If the rock is gabbro, the sand would be
very dark. In some cases only minerals will erode from the rock, especially
the very resistant quartz and feldspar minerals. In other cases, small rocks
will erode instead, because the minerals are too small to erode
individually. Basalt is an example, usually forming a dark sand composed of
very small pieces of basalt.
Students in the lower primary grades are usually amazed by sand, because it
seems so flexible. The feel of sand is also very important to young
children. It flows like water, yet it is not wet. The little pieces are
colorful. It is no wonder that children like to play in sand boxes.
Sand is the basic building block for sandstone, a type of sedimentary
rock. Sandstone forms when individual sand grains are squeezed together by
pressure and cemented. Sand can thus be thought of as "baby rock."
PROCEDURE:
- Ask students where water can be found. Many students will respond with
answers such as "fish tanks and bath tubs," but try to direct their
comments toward rivers, ponds, lakes and beaches. Where your children live
will obviously influence their responses.
- If any of your students have been to a beach or lake, have them
describe to the rest of the class if they played in the sand or the water.
You may also tell them that when you were a child, you played in the sand.
Describe how the sand felt to you as a child. Ask the students what sand
is composed of. Sand can be called "baby rocks." If the "baby rocks" were
cemented together, they would form sedimentary rocks. Sedimentary rocks
are commonly formed in or near water.
- Use the Sand Display kit to show students all the different sands that
have been collected from various beaches of California. You might
supplement this exercise with samples of sand that you may have collected.
- If you have a sand box you may want the students to explore the sand
in the box with a hand lens.
- Have the students color the worksheet. This exercise will guide them
to think about the "baby rocks" that are formed along the beach. Ask the
students to bring in baby food jars or jelly jars to class to be used for
the lab.
