2nd Nine Weeks Topics
MIAMI-DADE COUNTY PUBLIC SCHOOLS
Parent Resources
7 Grade Science Topic Highlights
Questions to ask your child
Layers of Earth
November
VI. Layers of Earth
A. Crust and Lithosphere
B. Mantle
C. Core
D. Comparing Layers of
the Earth
Question to learner: What are some features of the interior of the Earth?
Sample Response: There are three main layers of Earth’s interior; the crust, mantle, and
core. These layers vary greatly in size, composition, temperature and pressure (force
pressing on an area). The temperature and pressure inside Earth increases with depth. The
crust is the outer layer made of solid rock that includes both dry land and the ocean floor.
Earth’s mantle is made of rock that is very hot, but solid. The crust and uppermost mantle
are grouped into a single layer called the lithosphere. The core is made mostly of the metals
iron and nickel. It consists of two parts—a liquid outer core and a solid inner core. The outer
core is a layer of molten metal surrounding the inner core. The inner core is a dense ball of
solid metal. The movements in the liquid outer core create Earth’s magnetic field.
Plate Tectonics
November - December
VII.
Plate Tectonics
A. Continental Drift
B. Describing Tectonic
Plate Movement
C. Explaining Plate
D. Movement through
Heat Flow
Question to learner: How do moving plates change Earth’s Surface?
Sample Response: Earth’s tectonic plates are in slow, constant motion, driven by convection
currents (cyclical movement that transfers heat) of material in the mantle. Earth’s plates
move because they are on top of the large convection currents in Earth’s mantle and may
towards, away from or alongside neighboring plates resulting in different features on Earth's
surface. During subduction (the sinking of plates into the interior of Earth), gravity pulls
denser plate edges downward, into the mantle. Earth’s plates can carry ocean floor,
continents, or continents and oceans together. The convergence of plates can create
mountains, volcanoes, and deep ocean trenches. The spreading apart, divergence, or
plates can lead to ridges. Transform boundaries are the most common cause of
earthquakes as the tension build from plates sliding alongside each other is released.
Rock Cycle and Processes that Shape Earth’s Surface
December
VIII. Rock Cycle and Processes
that Shape Earth’s Surface
A. Rock Cycle
B. Review of Landforms
and Apply to Florida
C. How Humans Impact
the Earth
Question to learner: How are different types of rocks made?
Sample Response: Rocks are changed from one form to another by being exposed to various
amount of heat and pressure within the Earth. When small rock particles are exposed to high
pressure over long periods of time, sedimentary rock is formed. This involves Earth’s
surface being built up and broken down by physical and chemical weathering (the breaking
down of rock), erosion (movement of rock, i.e. by water or wind), and deposition (the laying
down of sediment). Rocks can be melted with enough heat creating magma. Igneous rocks
are formed when the molten rocks cools and hardens. A third type of rock, metamorphic
rock, is made when a combination of high pressure and high heat is applied to rocks. In
addition, humans plays a role in shaping the Earth’s surface such as deforestation,
urbanization, air, water quality, and changing the flow of water.
Division of Academics and Transformation – Department of Science
November-January Topic Highlights
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MIAMI-DADE COUNTY PUBLIC SCHOOLS
Parent Resources
7 Grade Science Topic Highlights
Age of Earth/Geological Time
January
IX. Age of Earth/ Geological
Time
A. Measuring the Age of
the Earth
B. Evidence of Changes
to Earth
Question to learner: How do scientists study Earth’s past?
Sample Response: The Earth has evolved over geologic time (many millions of years) due to natural
processes. Current methods for measuring the age of Earth and parts of the Earth include the Law of
Superposition and radioactive dating. According to the law of superposition, in horizontal sedimentary
rock layers the oldest layer is at the bottom. Each higher layer is younger than the layers below it
since rock layers and build by new sediment adding to the lower layers. This method doesn't provide
an exact or numerical age. Instead the Law of Superposition is used to determine relative ages of a
group of rocks such as "younger" or older". Radioactive dating uses a chemical analysis of rocks to
determine an approximate numerical age.
Division of Academics and Transformation – Department of Science
November-January Topic Highlights
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