BACKGROUND:
Rocks are solid matter. Some feel heavy, some do not.
Rocks are made of minerals. However, many times the minerals are very
small and can only see with a microscope.
Rocks are forming around the world all the time.
Volcanoes bring new lava to the Earth's surface which will later cool to
become rock. Mud will become hard and eventually become a rock. Sand grains
will get cemented together and become sandstone with time. Even humans will
mix cement, gravel, and sand and make a human rock, called concrete. Rocks
are all around us. We live on rocks. Soil comes from rock, dirt comes from
rock, and buildings (other than those made of wood) come from rocks. Rocks
are more important to our everyday lives than we realize.
Igneous rocks are considered the "Mother" of all
rocks. Molten material cools down and becomes either a volcanic or plutonic
igneous rocks. The term volcanic and plutonic help to understand the origin
of where the rock cooled down. For instance, if magma cooled inside the
Earth it is called plutonic. If molten rock (lava) moved upwards in a
volcano and cooled it is called a volcanic rock.
PROCEDURE:
- Remind students that they examined rocks from volcanoes when they
studied plate tectonics. Those rocks are called volcanic rocks because
they cooled outside of the volcano. Magma inside the Earth can also cool
inside of the Earth and create rocks called plutonic rocks. All rocks that
are cooled from magma or lava are called igneous rocks. Both volcanic and
plutonic rocks are igneous rocks. Repeat these words several times. It is
not as important for the students to remember the words as it is to
introduce the terms.
- You may want to have students bring in pictures of volcanoes from magazines or from
the Internet. Draw the following picture on the board to reinforce the
main concepts of the lab.
