Space, rocks, weather and hazards: unofficial questions on the five selected-response subareas of Oklahoma's OSAT Earth Science test, field 108.
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Unofficial practice questions, not affiliated with Oklahoma's Office of Educational Quality and Accountability or Pearson. Bank checked October 13, 2026.
A class sets a stream table at three different slopes and measures how much sand each flow carries away. Which is the independent variable?Wikipedia, Dependent and independent variables, In modeling and statistics. Written to the OSAT Earth Science (108) framework, competency 0001
A hiker compares two trails on a contour map. On trail A the lines are crowded together; on trail B they are spread far apart. What can she tell?Wikipedia, Contour line, lead. Written to the OSAT Earth Science (108) framework, competency 0002
A student finds that years with more sunspots were also the wetter years in her county. What may she conclude from that pattern alone?Wikipedia, Correlation does not imply causation, lead. Written to the OSAT Earth Science (108) framework, competency 0004
Before students test rock samples with dilute hydrochloric acid, the teacher looks up the acid's hazards and safe handling. Which document lists them?Wikipedia, Safety data sheet, lead. Written to the OSAT Earth Science (108) framework, competency 0001
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Subarea I: Science practices and engineering, continued
Five readings from a homemade rain gauge agree closely with each other, but all are about 5 mm above the true rainfall. How should the readings be described?Wikipedia, Accuracy and precision, lead. Written to the OSAT Earth Science (108) framework, competency 0002
In the ice–albedo feedback, a small warming grows larger on its own. Which step makes the loop reinforce itself?Wikipedia, Ice–albedo feedback, lead. Written to the OSAT Earth Science (108) framework, competency 0004
On a topographic map, the heavy contour lines labeled 400 m and 500 m have four lighter lines between them. What is the contour interval?Wikipedia, Contour line, lead. Written to the OSAT Earth Science (108) framework, competency 0002
Students build a small working model of a weather station mast and test it in front of a fan before making the full-size mast. What is the small model?Wikipedia, Prototype, lead. Written to the OSAT Earth Science (108) framework, competency 0003
Town engineers run a feasibility study on three flood barrier concepts. A concept goes on to the design phase only if it is an achievable idea and meets one more test. Which test?Wikipedia, Engineering design process, Feasibility studies. Written to the OSAT Earth Science (108) framework, competency 0003
Which claim about a creek near school could a student investigation test, because an observation could contradict it?Wikipedia, Falsifiability, lead. Written to the OSAT Earth Science (108) framework, competency 0001
Subarea II: Space systems 11
A harbor master expects the month's largest tidal ranges, the spring tides. At which two phases of the Moon do they come?NOAA National Ocean Service, What are spring and neap tides?. Written to the OSAT Earth Science (108) framework, competency 0008
A Hertzsprung–Russell diagram puts hot, bright stars at the upper left and the main sequence on the diagonal. In which region are white dwarfs found?Wikipedia, Hertzsprung–Russell diagram, lead. Written to the OSAT Earth Science (108) framework, competency 0006
An icy body orbits the Sun with a semi-major axis of 9 AU. Earth, at 1 AU, takes 1 year. By Kepler's third law, about how long does one orbit take it?Wikipedia, Kepler's laws of planetary motion, lead. Written to the OSAT Earth Science (108) framework, competency 0007
Earth is closest to the Sun in January, yet January is midwinter in Oklahoma. What does cause the seasons?Wikipedia, Season, lead and Elliptical Earth orbit. Written to the OSAT Earth Science (108) framework, competency 0008
Earth reaches perihelion, its closest point to the Sun, in January. By Kepler's second law, when does Earth move fastest along its orbit?Wikipedia, Kepler's laws of planetary motion, lead, with Season, Elliptical Earth orbit. Written to the OSAT Earth Science (108) framework, competency 0007
Galaxy B lies twice as far from Earth as galaxy A. By Hubble's law, how do their speeds of recession compare?Wikipedia, Hubble's law, lead. Written to the OSAT Earth Science (108) framework, competency 0005
In 1964 two radio astronomers found a faint microwave glow coming from every direction of the sky. Why does that glow matter to cosmology?Wikipedia, Cosmic microwave background, lead. Written to the OSAT Earth Science (108) framework, competency 0005
Long-period comets fall toward the Sun from every direction of the sky. Which distant reservoir is thought to supply them?Wikipedia, Oort cloud, lead. Written to the OSAT Earth Science (108) framework, competency 0007
Models of stellar evolution follow the Sun beyond its red giant phase. What do they suggest it will become next?Wikipedia, Sun, lead. Written to the OSAT Earth Science (108) framework, competency 0006
What structure do stars in the Milky Way's innermost 10,000 light-years form?Wikipedia, Milky Way, lead. Written to the OSAT Earth Science (108) framework, competency 0005
Which nuclei were made in the first minutes after the Big Bang, before any star had formed?Wikipedia, Nucleosynthesis, lead. Written to the OSAT Earth Science (108) framework, competency 0006
Subarea III: Geological systems 11
A cold, dense plate sinks into the mantle at an ocean trench and drags the rest of the plate behind it. What is this force, found to be the strongest of those driving plate motion?Wikipedia, Slab pull, lead. Written to the OSAT Earth Science (108) framework, competency 0010
A long, winding ridge of layered sand and gravel crosses a plain that an ice sheet once covered. Which landform is it?Wikipedia, Esker, lead. Written to the OSAT Earth Science (108) framework, competency 0011
A road cut exposes flat, undeformed layers: shale at the base, sandstone in the middle and limestone on top. Which layer is the oldest?Wikipedia, Law of superposition, lead. Written to the OSAT Earth Science (108) framework, competency 0009
During the Great Oxidation Event, free oxygen first built up in Earth's atmosphere. Which organisms are inferred to have caused it?Wikipedia, Great Oxidation Event, Overview. Written to the OSAT Earth Science (108) framework, competency 0009
Earthquake waves reach the boundary between the mantle and the core. What happens there to the P waves and to the S waves?Wikipedia, Shadow zone, lead. Written to the OSAT Earth Science (108) framework, competency 0010
The oldest volcanic rocks on Kauai are about 5.5 million years old, and the islands grow younger toward the Big Island of Hawaii. What explains the age pattern?U.S. Geological Survey, This Dynamic Earth, "Hotspots": Mantle thermal plumes. Written to the OSAT Earth Science (108) framework, competency 0010
On the Mohs scale calcite is 3 and fluorite is 4. An unknown mineral scratches calcite but is scratched by fluorite. Where does its hardness fall?Wikipedia, Mohs scale, Reference minerals. Written to the OSAT Earth Science (108) framework, competency 0011
Rhyolite and granite are both rich in silica. How does rhyolite differ from granite?Wikipedia, Rhyolite, lead and Description. Written to the OSAT Earth Science (108) framework, competency 0011
Surveys in the 1950s mapped zebra-stripe magnetic patterns in the rocks of the ocean floor. What did geologists propose in 1963 as the cause of the stripes?U.S. Geological Survey, This Dynamic Earth, Magnetic stripes and isotopic clocks. Written to the OSAT Earth Science (108) framework, competency 0010
Uranium-235 decays to lead-207; its half-life is about 700 million years. A zircon crystal holds one quarter of its original uranium-235. About how old is it?Wikipedia, Radiometric dating, Fundamentals and Uranium–lead dating method. Written to the OSAT Earth Science (108) framework, competency 0009
Water seeps into cracks in a cliff and freezes night after night until blocks split off. What makes freezing water able to break rock?Wikipedia, Frost weathering, Volumetric expansion. Written to the OSAT Earth Science (108) framework, competency 0011
Subarea IV: Atmosphere and water 11
A fisheries biologist wants to predict coastal upwelling. Under which wind condition does NOAA say upwelling along a coast is at its best?NOAA National Ocean Service, What is upwelling?. Written to the OSAT Earth Science (108) framework, competency 0015
A parcel of dry air at 25 °C is pushed 2 km up a mountain slope without exchanging heat. At the dry adiabatic lapse rate of 9.8 °C per km, what is its temperature at the top?Wikipedia, Lapse rate, lead. Written to the OSAT Earth Science (108) framework, competency 0013
A well is drilled into an aquifer confined between layers of clay, and water rises up the well without a pump. What is such an aquifer called?U.S. Geological Survey, Water Science School, Aquifers and Groundwater. Written to the OSAT Earth Science (108) framework, competency 0015
Air circulates from near the South Pole toward the equator. Which way does Earth's rotation deflect it in the Southern Hemisphere?NOAA National Ocean Service, Currents tutorial, The Coriolis Effect. Written to the OSAT Earth Science (108) framework, competency 0012
An instrument holds two thermometers: one dry, one kept moist by a wet wick. What is the instrument, and what does it measure?Wikipedia, Hygrometer, Psychrometer (wet-and-dry-bulb thermometer). Written to the OSAT Earth Science (108) framework, competency 0014
Deep-ocean currents of the global conveyor belt are driven by differences in the density of seawater. Which two properties control that density?NOAA National Ocean Service, Currents tutorial, Thermohaline Circulation. Written to the OSAT Earth Science (108) framework, competency 0015
In the Hadley cell of the atmosphere, where does air rise and where does it sink?Wikipedia, Hadley cell, lead. Written to the OSAT Earth Science (108) framework, competency 0012
Moist wind from the sea blows across a high mountain range. On which side of the range does the dry rain shadow lie?Wikipedia, Rain shadow, lead. Written to the OSAT Earth Science (108) framework, competency 0014
On a clear night the air near the ground cools until its temperature reaches the dew point. What has its relative humidity become?Wikipedia, Dew point, lead and Humidity. Written to the OSAT Earth Science (108) framework, competency 0013
On a weather map, a blue line edged with triangles is moving toward Tulsa. What is about to arrive?Wikipedia, Cold front, lead. Written to the OSAT Earth Science (108) framework, competency 0014
Temperature falls with height through the troposphere but rises with height through the stratosphere. What warms the stratosphere?NOAA JetStream, Layers of the Atmosphere. Written to the OSAT Earth Science (108) framework, competency 0012
Subarea V: Natural hazards and human impact 9
A geothermal plant runs on heat from deep inside the earth. According to the U.S. Energy Information Administration, what produces that heat?U.S. Energy Information Administration, Geothermal explained. Written to the OSAT Earth Science (108) framework, competency 0017
A tornado crosses central Oklahoma. How does the National Weather Service arrive at its EF rating?National Weather Service, Norman, Oklahoma, The Enhanced Fujita Scale (EF Scale). Written to the OSAT Earth Science (108) framework, competency 0016
A tsunami crosses the deep ocean and nears a coast. What happens to its waves as the water grows shallow?NOAA National Ocean Service, What is a tsunami?. Written to the OSAT Earth Science (108) framework, competency 0016
A utility compares fuels by the carbon dioxide released for each unit of energy. By U.S. Energy Information Administration figures, which fossil fuel releases the least?U.S. Energy Information Administration, Natural gas explained, Natural gas and the environment. Written to the OSAT Earth Science (108) framework, competency 0017
Each summer a low-oxygen "dead zone" forms where a great river empties into the sea. What is the primary cause of the dead zones that people create?NOAA National Ocean Service, What is a dead zone?. Written to the OSAT Earth Science (108) framework, competency 0019
Earth's surface averages about 15 °C. About what would it be if greenhouse gases and clouds absorbed none of the radiation the surface emits?Wikipedia, Greenhouse effect, Measurement. Written to the OSAT Earth Science (108) framework, competency 0016
The Keeling Curve is a record used to monitor a human impact on the atmosphere. What does it track, and where?Wikipedia, Keeling Curve, lead. Written to the OSAT Earth Science (108) framework, competency 0019
The ocean takes up part of the carbon dioxide that burning fossil fuels adds to the air. What does this do to seawater chemistry?NOAA National Ocean Service, What is ocean acidification?. Written to the OSAT Earth Science (108) framework, competency 0018
Oklahoma has had more induced earthquakes than any other state. To which practice does the U.S. Geological Survey trace most of them?U.S. Geological Survey, FAQ, Does fracking cause earthquakes?. Written to the OSAT Earth Science (108) framework, competency 0018
How this list was compiled: Our own questions, written to the test design and framework of Oklahoma Subject Area Tests field 108, Earth Science, in the study guide on the Certification Examinations for Oklahoma Educators website (https://www.ceoe.nesinc.com/Content/StudyGuide/OK_SG_OBJ_108.htm, copyright 2019 Office of Educational Quality and Accountability and Pearson Education, Inc.; test page https://www.ceoe.nesinc.com/TestView.aspx?f=HTML_FRAG/OK108_TestPage.html, read 2026-10-13): 80 selected-response questions and 1 constructed-response assignment in 4 hours, passing score 240, no reference materials; selected response weighs Science Practices and the Engineering Process (competencies 0001 to 0004) 16%, Space Systems (0005 to 0008) 18%, Geological Systems (0009 to 0011) 18%, Atmospheric and Hydrological Systems (0012 to 0015) 18% and Natural Hazards and Human Environmental Interaction (0016 to 0019) 15%, and the constructed response (0020) 15%. The bank holds 52: 10, 11, 11, 11 and 9, with two to four for each of the 19 selected-response competencies. Every fact was read on the public page named under its question: pages of the U.S. Geological Survey, NOAA's National Ocean Service and JetStream, the National Weather Service office in Norman, Oklahoma, and the U.S. Energy Information Administration for 15 questions, and the named Wikipedia articles for the rest; each calculation was worked a second time. Licence: Questions, choices and explanations are original work of this site.
How it works
This OSAT Earth Science practice test has 52 original questions on field 108's 19 selected-response competencies, fifteen answered from USGS, NOAA and EIA pages. It is unofficial and not affiliated with Oklahoma's Office of Educational Quality and Accountability or Pearson.
Read the full guide
Five subareas of nearly equal weight
Field 108's framework, read on the CEOE site on October 13, 2026, weights Space Systems, Geological Systems, and Atmospheric and Hydrological Systems at 18% of the test each. Science Practices and the Engineering Process is 16%, and Natural Hazards and Human Environmental Interaction 15%. The 52 questions here split 10, 11, 11, 11 and 9.
The lesson-plan assignment is left out
The last 15% of the test is one written assignment: an analysis of a lesson plan with student work or assessments. No question here practices it.
Competency 0018 lists fracking and increased earthquakes among human effects on the lithosphere; one question here asks what the USGS reports for Oklahoma.
Questions and answers
How many questions are on the OSAT Earth Science test?
80 selected-response questions and one constructed-response assignment, by the test page for field 108. Testing time is 4 hours, after a 15-minute tutorial, and some questions may be unscored trial questions.
What is the passing score for OSAT Earth Science?
The test page gives 240. Because the written assignment is part of that score, right answers on this page cannot be converted to it, and a round here closes without a pass or fail.
What is on the OSAT Earth Science test?
Science practices and engineering design; the universe, stars, the solar system and the Earth, Moon and Sun; Earth history, plate tectonics, rocks and landforms; the atmosphere, weather, climate and water; then natural hazards, energy resources and human impact.
Is astronomy on the OSAT Earth Science test?
Yes. Subarea II, Space Systems, is 18% of the test. Its competencies 0005 to 0008 cover the universe, stellar characteristics, the solar system, and the Earth, Moon and Sun system.
Can you use a calculator on the OSAT Earth Science test?
The test page for field 108 gives its reference materials as none and names no calculator. The few calculations on this page need only simple arithmetic.