Big Ideas in 6th Grade Earth Science

Key Concepts / Descriptions / Sub-Concepts
  1. Rocks and landforms are part of the geosphere but are changed over time by interaction with the hydrosphere, atmosphere and biosphere through constructive and destructive forces.
(Rocks and Landforms) / There are three types of rock: sedimentary, igneous, and metamorphic. Sedimentary rocks form from the lithification of various types of sediment. Igneous rocks form by the solidification of magma. Metamorphic are rocks that have been changed by heat or pressure while remaining solid. Rock bears evidence of the minerals, temperatures, and forces that created it.
Some changes in the solid earth can be described as the "rock cycle." Rocks at Earth's surface weather, forming sediments that can be buried, then compacted, heated, and often recrystallized into new rock. Eventually, those new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues.
Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion from the motion of liquid and frozen water and wind over very long times.
Rivers and glaciers are strong erosional agents that shape the land over time. The sedimentary particles they create and carry are eventually deposited in river deltas, flood plains, or ocean beds, as part of the rock cycle.
Human activities, such as reducing the amount of forest cover, and intensive farming, have changed the earth's land.
Adapted from National Science Education Standards, National Research Council (1996) and Benchmarks for Science Literacy, American Association for the Advancement of Science – Project 2061 (1993). / a)The Earth’s crust is made of rocks which can be igneous, sedimentary or metamorphic. (Benchmark 4.3)
b)Different types of rocks occur in different regions. (Benchmark 4.3)
c)Rocks form and break down by processes collectively known as the “rock cycle”. (Benchmark 4.3)
d)Rocks break down through a process called weathering, which is part of the rock cycle. There are three types of weathering: physical, chemical, and biological. Different types of rock might be affected differently by weathering processes. (Benchmark 4.3)
e)Weathering and other erosional processes involve the geosphere, hydrosphere, atmosphere and biosphere. Erosion can be the result of running water, wind, glaciers, and gravity. Some landforms are shaped by erosion. (Benchmark 4.3)
f)Delta and floodplains are formed by sediment deposition. (Benchmark 4.3)
g)Glaciers are masses of ice that flow slowly under their own weight and can erode and deposit particles to form landforms. (Benchmark 4.3)
  1. The Earth is anevolving planet undergoing constant change due to the heat dynamics within its interior and the associated movement oflithosphericplates that make up its crust.
(Our Dynamic Planet) / Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly, or that are too vast to be changed deliberately, or that are potentially dangerous.
Seismic wave evidence shows that Earth is layered with a lithosphere; convecting mantle; and dense, metallic core. Convection heat flow and movement of material within the Earth cause earthquakes and volcanic eruptions and create mountains and ocean basins.
Seismic waves travel at a certain rate in a uniform material, are refracted when they enter material of a different density, and carry energy with them as they move through a material
Lithospheric plates on the scales of continents and oceans constantly move at rates of centimeters per year in response to movements in the mantle. Many major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.
Rocks at the Earth's surface weather, forming sediments that can be buried, then compacted, heated, and often recrystallized into new rock. Eventually, those new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues.
Earth processes we see today, including the movement of lithospheric plates, are similar to those that occurred in the past.Evidence common to widely separated continents, including fossils, mountain chains, and glacial deposits, provide evidence of continental drift over time.
Adapted from National Science Education Standards, National Research Council (1996) and Benchmarks for Science Literacy, American Association for the Advancement of Science – Project 2061 (1993). / a)Evidence from fossils and rocks can show how continents have drifted apart over time. (Benchmark 4.5)
b)Earth’s crust is not one continuous piece but exists as large and small pieces or plates. (Benchmark 4.4)
c)Convection currents within Earth’s mantledrive the movement of lithospheric plates. (Benchmark 4.4)
d)Earthquakes, mountains, and/or volcanoes mostly occur at lithosphericplate boundaries. (Benchmark 4.4)
e)Volcanoes result from the eruption of molten rock, volcanic fragments, and gases at the Earth’s surface. (Benchmark 4.3)
f)Modeling can be used in science to reveal and measure and infer something that cannot be seen. (Benchmark 5.4)
  1. Earth, and its Moon, is one of nine planets in the Solar System, which is part of the Milky Way galaxy, whose central body is the Sun around which these planets orbit due to gravitational forces.
(Earth in Space: Astronomy) / Earth is a moving, spherical planet,with unique features that distinguish it from other planets in the Solar System.It is the third planet from the Sun in a system that includes the Moon, the Sun, eight other planets and their moons, and smaller objects, such as asteroids and comets.
Earth is the only body in the solar system that appears to support life. The other planets have compositions and conditions very different from the Earth's.
Earth’s moon is pitted with the impact of craters that are the remains of collisions between an asteroid, comet, or meteorite and the Moon long ago. Its orbit around the Earth, once in about 28 days changes what part of the Moon is lighted by the Sun and how much of that part can be seen from the Earth-the phases of the Moon.The gravitational pull of the Moon relative to that of Earth’s, causes ocean tides.
The Sun, an average star, is the central and largest body in the Solar System. It is the major source of energy for phenomena at the Earth's surface.Energy from Earth’s interior also dives surface processes.
Gravity and forward motion are that keeps planets in orbit around the Sun and governs the rest of the motion in the Solar System. Gravity alone holds us Earth's surface and explains the phenomena of the tides.
Earth is a system within a Solar System which is, in turn, within a galaxy. There are millions of other galaxies in the universe
The primary cause of the seasons is the 23.5 degree of the Earth's rotation axisin relation to its elliptic orbit round the Sun.
Adapted from National Science Education Standards, National Research Council (1996) and Benchmarks for Science Literacy, American Association for the Advancement of Science – Project 2061 (1993). /

a)The surface of the Moon has craters which are impacts of asteroids, comets, and meteorites. (Benchmark 4.13)

b)The Sun is a star and the central and largest body in the Solar System. (Benchmark 4.14)

c)Gravity and forward motion are the forces that keep planets in orbit around the Sun. (Benchmark 4.14)

d)Earth rotates around its axis and orbits the Sun. (Benchmark 4.14)

e)Gravity, which is lower on the Moon, binds it to the Earth.(Benchmark 4.14)

f)The planets all orbit the Sun and are different distances from the Sun and each other.(Benchmark 4.15)

g)Earth is a moving, spherical planet, third from the Sun and different from other planets in size and distance in the Solar System. (Benchmark 4.13)
h)Telescopes are used to monitor the Earth system and study the universe. (Benchmark 4.16)
  1. All of planet Earth’s water (the hydrosphere), is essential for life, circulates through Earth systems, shapes the land, and is used as both an essential and non-essential resource by humans.
(Water as a Resource) / Three-fourths of Earth’s surface is covered by a relatively thin layer of water, some of it frozen. Water circulates through the crust, oceans, and atmosphere in what is known as the "water cycle”. Heat energy from the sun causes water to evaporate from the Earth's surface, rise and lose heat as it moves to higher elevations, condense into rain or snow, and fall to the surface where it collects in rivers and lakes, soil, and porous layers of rock. Much of it eventually flows back into the oceans over long periods of time.
Because of gravity, liquid water flows “downhill” seeking the easiest pathway. Gravity channels water over the land taking the line of least resistance and, in so doing shapes it into a variety of landforms. Landform features are plotted on topographic maps which can be used to indicate the boundaries of watersheds. A watershed includes all the sources of liquid water that feed into a water supply including precipitation, streams, rivers, lakes and groundwater. Water is a solvent. It can dissolve some substances but not others. As it passes through the water cycle it dissolves minerals and gases and carries them to the oceans.
Because of water’s relative density, less-dense then water objects can float on or near its surface while more-dense than water objects sink. Water’s surface tension can sometimes support small more-dense objects including some insects.
Fresh water, limited in supply, is essential for life and also for most industrial processes. Its source is usually a watershed. Rivers, lakes, and groundwater can be depleted or polluted, becoming unavailable or unsuitable for life.While physical, chemical, and biological methods can be used to clean water,the processes can be difficult and costly.
Adapted from National Science Education Standards, National Research Council (1996) and Benchmarks for Science Literacy, American Association for the Advancement of Science – Project 2061 (1993). / a)Living things, including humans, need water to survive and some uses of water are more essential to life than others. (Benchmarks4.12)
b)The water supply comes from a watershed (all the sources of water that feed into a supply). (Benchmark 4.1 & 4.11)
c)Pollutants, which can come from a variety of sources, can enter the water supply at any point in a watershed. (Benchmark 4.11)
d)Water moves because of gravity and percolates down through soil to form groundwater. (Benchmark 4.1 & 4.11)
e)Water circulates through the Earth system in three different states, solid, liquid, and vapor, known as the water cycle. (Benchmarks 4.2 & 4.12)
f)Water has unique properties such as it can dissolve some substances but not others. (Benchmark 4.12)
g)Water quality, and quantity, is affected by both humans and “natural” events. (Benchmark 5.5)
h)It is possible to analyze the water supply, and remove pollutants, using physical, chemical, and biological methods. (Benchmark 5.5)
  1. Weather comprises all the various phenomena that occur in the atmosphere. Climate represents the average pattern of weather variation at a certain location over several decades.
(Climate and Weather) / Weather is studied and measured using specifically designed instruments, satellite images, radar data and many other tools. Weather data are recorded and interpreted on weather maps which show these data using symbols, isotherms which connect points of equal temperature and isobars which connect points of equal air pressure. These data are used to produce weather reports and weather forecasts.
Air pressure decreases with altitude because there is less air above pressing down. The water cycle, driven by heat energy, plays an important role in determining climatic and weather patterns. Clouds, formed by the condensation of water vapor, affect weather and climate. General circulation of the atmosphere and oceans has a strong influence on climate around the world.
Global patterns of atmospheric movement influence local weather and climate. Warmer air masses rise over cooler air masses. Winds blow because areas of higher air pressure move toward areas of lower air pressure in the atmosphere. Climate can be affected both by events which originate within the Earth system, including human activity, and by Earth’s interactions with the Sun.Climate is affected by elevation, latitude, and proximity to water and mountains.
Fossils, ice cores, tree rings and ocean sediment cores can provide evidence of past climates. Even relatively small changes in atmospheric or oceanic characteristics can have widespread effects on climate if the change lasts long enough.
Adapted from National Science Education Standards, National Research Council (1996) and Benchmarks for Science Literacy, American Association for the Advancement of Science – Project 2061 (1993). / a)Different aspects of weather can be measured using specifically designed instruments. (Benchmark 4.7 & 4.9)
b)The water cycle, driven by heat energy, consists of evaporation, condensation, and precipitation. (Benchmarks 4.2 & 4.8)
c)Clouds within the water cycle affect weather and climate. (Benchmark 4.8)
d)Climate is an established weather pattern that has remained fairly constant over several decades. (Benchmark 4.10)
e)Weather data, including satellite images and radar data, is turned into weather maps, weather reports, and weather forecasts. (Benchmark 5.4)
  1. Geoscientific literacy is knowing how the Earth works as a system in which humans as citizens have a responsibility to sustain the delicate balance of these systems through careful stewardship, informed decision making, and the wise use of Earth’s resources.
/ The idea of Earth, integrated within the Solar System and even larger systems, is fundamental to geoscience. A systems-based approach provides the context for investigating and Earth’s four major systems: geosphere, hydrosphere, atmosphere, and the biosphere and the astronomical systems within which planet Earth resides.
The geosphere is that part of the Earth system which includes the crust, mantle, and inner and outer core. The hydrosphere is the part which includes the planet’s water, including oceans, lakes, rivers, ground water, ice, and water vapor. The atmosphere is that part which includes the mixture of gases that surround the planet. The biosphere is that part of the Earth system that includes all living things, including plants, animals, and all other organisms.
Physical, chemical, and biological processes act within and among these four component systems on a wide range of time scales to continuously change Earth’s crust, oceans, atmosphere, and living organisms. These processes are powered by energy from the Sun and Earth’s own inner heat. There are physical and relationships among Earth, its moon, the sun, the solar system, and beyond some of which are visible from Earth or from using technology in outer space.
Earth is a dynamic planet which has evolved over 4.6 billion years. This evolution has left a geologic record of its history that geoscientists can interpret.
Humans depend upon the Earth systems to survive. This includes the geosphere’s natural resources, and soil, the hydrosphere’s water, the atmosphere’s oxygen and other gases, and upon the biosphere for food.
Adapted, in part, from National Science Education Standards, National Research Council (1996) and Benchmarks for Science Literacy, American Association for the Advancement of Science – Project 2061 (1993). / a)The Earth and the Solar System are a set of closely linked systems
b)Earth’s processes are powered by two sources: the Sun, and Earth’s own inner heat.
c)The geology of the Earth is dynamic, and has evolved over 4.6 billion years.
d)The geological evolution of the Earth has left a record of its history that geoscientists interpret.
e)We depend upon Earth’s resources - both mined and grown.
  1. Inquiry involves engaging in scientifically oriented questions, giving priority to evidence in responding to questions, formulating explanations based on evidence, connecting explanations to scientific knowledge, and communicating and justifying explanations.
(Abilities to do Scientific Inquiry) / Learners are engaged by scientifically oriented questions. Scientifically oriented questions center on objects, organisms, and events in the natural world; they connect to the science concepts described in the content standards. They are questions that lend themselves to empirical investigation, and lead to gathering and using data to develop explanations for scientific phenomena.
Learners give priority to evidence, which allows them to develop and evaluate explanations that address scientifically oriented questions. Science distinguishes itself from other ways of knowing through use of empirical evidence as the basis for explanations about how the natural world works.
Learners formulate explanations from evidence to address scientifically oriented questions. Scientific explanations are based on reason. They provide causes for effects and establish relationships based on evidence and logical argument.
Learners evaluate their explanations in light of alternative explanations, particularly those reflecting scientific understanding. Evaluation, and possible elimination or revision of explanations, is one feature that distinguishes scientific from other forms of inquiry and subsequent explanations.
Learners communicate and justify their proposed explanations. Scientists communicate their explanations in such a way that their results can be reproduced. This requires clear articulation of the question, procedures, evidence, proposed explanation, and review of alternative explanations. It provides for further skeptical review and the opportunity for other scientists to use the explanation in work on new questions.
Adapted from Inquiry and the National Science Education Standards (2000) by the National Research Council and published by the NationalAcademy Press. / a)Ask scientifically oriented questions and state hypotheses that lead to different types of investigations.
b)Use appropriate tools, technologies, and metric measurements to gather and organize data and report results.
c)Interpret and evaluate data to formulate logical conclusions.
d)Demonstrate that scientific ideas are used to explain observations and predict future events.
e)Identify and evaluate alternative explanations and procedures for solving problems or conducting scientific investigations.
f)Communicate results of scientific investigations in appropriate ways, such as written reports, graphic displays, and oral presentations.
  1. The development of scientific knowledge is based on questioning current knowledge, using empirical facts to develop logical theories, and verifying observations and claims.
(Understandings about the Nature of Science) / Although in some cases the understandings about inquiry and the nature of science appear to be parallel to the abilities to do scientific inquiry, they actually represent much more. Understandings about scientific inquiry and the nature of science represent how and why scientific knowledge changes in response to new evidence, logical analysis, and modified explanations debated within a community of scientists. The focus is on the nature of the work scientists do and how it connects to the work students do when they are conducting their own investigations. The nature of science includes opportunities to learn about the work of scientists in specific contexts that illustrate a question asked by scientists, how they went about addressing the question, and what they learned as a result related to the question.
Adapted from Inquiry and the National Science Education Standards (2000) by the National Research Council and published by the NationalAcademy Press. / a)Explain how controlled experiments must have comparable results when repeated.
b)Describe how scientific knowledge changes as new knowledge is acquired and previous ideas are modified.
c)Explain how models can be used to predict changes.
d)Describe examples of interrelationships among science, technology, and human activity that affect the world.
e)Describe how people in different cultures and at different times in history have made contributions to scientific advancements.

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