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The FOSS Pebbles, Sand, and Silt module provides experiences
that heighten students' awareness of rocks. They will come to know
rock by a host of names and in a variety of sizes. Pebbles and sand
are the same stuff: just different in the size of the particles. In the
end, they do projects that demonstrate how people use earth materials in their daily
lives.
In activity 1, First Rocks, students are introduced to
the mineral portion of the planet on which they live. Students
investigate several kinds of rocks and begin to develop an
understanding of the properties of rocks. They rub rocks, wash rocks,
sort rocks, and describe rocks.
In activity 2, River Rocks, students investigate a river
rock mixture consisting of earth materials of different sizes. They
separate the rocks using a series of three different screens. Students
discover five sizes of materials: large pebbles, small pebbles, large
gravel, small gravel, and sand. They add water to sand in a vial,
shake it, and let it settle. A layering of materials allows them to
see and feel silt particles, which are smaller than sand. Even smaller
rock particles, clay, are also investigated.
In activity 3, Using Rocks, students learn how people
use earth materials to construct objects. Students make rubbings from
sandpaper, sculptures from sand, decorative jewelry from clay, and
bricks from clay soil. They go on a schoolyard fleld trip to look for
places where earth materials occur naturally and where people have
incorporated earth materials into building materials.
In activity 4, Soil Explorations, students put together
and take apart soils. They are introduced to humus as an ingredient
in soil. The other ingredients of soil are the earth materials they
have investigated (clay, silt, sand, gravel, and pebbles). Homemade
and local soils are studied and compared, using techniques introduced
in activity 2 (shaking, screening, settling out in water).
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