BACKGROUND:
Rocks record the Earth’s history when those rocks where formed. When
students get a piece of rock in lab they need to associate different
environments with that rock. In the first grade, students need to begin
grouping these rocks into basic environments of sedimentary, igneous, and
metamorphic. Although sedimentary is the most common rock found on the
surface of the Earth, students can find most of the groups very easily. It
is very common for buildings to be made of rocks. In cities, you can walk along
buildings and see the different types of rocks, even if they did not form in
that city.
Discuss with the students that rocks have key
characteristics, just like
minerals, but that identifying rocks is much more difficult. In this lab
they will become familiar with the key characteristics of a small group of
igneous, sedimentary, and metamorphic rocks.
PROCEDURE:
- Review the rocks on the pre lab identification sheets. You may want to
go over some of the characteristics described below.
BLACK, GLASSY - black-the color; glassy - have students imagine
broken glass
RED, HOLES - red-the color; holes, - like Swiss cheese
LARGE MINERALS - visible, obvious minerals
WHITE, FLAT, LIGHT - white-the color; flat - as a pancake; _ like
a balloon
PEBBLES, GLUED - sand size; sand grains look like they are pasted
together
FLAT, LAYERS - pancakes stacked on top of each other
SHINY - like a new car
WHITE AND GRAY MINERALS - the minerals are large enough to see
and are white and gray; fizz - if you have dilute HCl(can be bought in
a hardware store as Muriatic Acid - Cement Cleaner) pour just a drop on
a specimen so students can see it fizz (DO NOT LET CHILDREN PLAY WITH
HCl).
- See if the students can match the rocks in their packets with the
characteristics on the identification sheet. Frequently check on their
process. as they decide which rock belongs where.
- Discuss with students which rocks belong to which group as grouped
below:
IGNEOUS - granite, scoria, obsidian
SEDIMENTARY - sandstone, conglomerate, shale
METAMORPHIC - marble, schist, gneiss
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