Earth science involves the study of large-scale physical structures and processes. It includes geology, meteorology, oceanography, atmospheric science, and astronomy. The latter is included to understand Earth-moon-sun relationships and Earth’s place in the solar system, galaxy, and universe.
The large-scale structure of the Earth is a molten core surrounded by a hot mantle and overlain by a thin crust of solid rock continents and ocean basins.
The Earth consists of minerals. In the core, and mantle, they are heated to form a liquid called magma. On the crust, these minerals cool to form rocks. The ocean basins are filled with liquid water. Surrounding the Earth is a thin atmosphere containing mostly nitrogen and oxygen.
Important Terms and Ideas: core, mantle, crust, role of seismology in understanding these; continents; rock cycle, igneous, metamorphic, sedimentary; topographic maps; radioactive decay, source of interior heat; composition of ocean waters; layers of the atmosphere
The Earth can be studied as a set of interrelated systems. Rocks and magma interact to form land masses such as continents. The oceans and the atmosphere interact to distribute heat energy around the globe.
Important Terms and Ideas: biomes and climate zones; oceanic zones, estuaries, continental shelf, abyssal plain, trenches; atmospheric zones, westerlies, doldrums, trade winds; high and low pressure weather systems
Earth processes transfer heat, water, and solid material around the globe.
Important Terms and Ideas: plate tectonics, continental drift, subduction zones, earthquakes, and volcanoes; weathering, erosion, deposition, glaciation; water cycle; carbon cycle; heat budgets, greenhouse effect;
Geologic structures of the Earth include mountains, valleys, folds, and faults. They result from bending and other deformations of rock layers. Some of these deformations are caused by glaciers.
Important Terms and Ideas: syncline, anticline; reverse fault, thrust fault, strike-slip fault, rift valley; glaciers, moraines, eskers
Earth Time Concepts
Various methods of radioactive dating indicate the age of the Earth to be roughly five billion years. The fossil record shows that many life forms have lived on Earth but have become extinct.
Important Terms and Ideas: methods of radioactive dating; geologic eras and periods; fossilization
We can get a better understanding of the processes on our planet when we compare the Earth to the nearby planets Venus and Mars. Both planets seem to have similar processes but taken to extremes. Study of the composition of asteroids and meteors gives insight into the composition of Earth early in its history.
The Solar System
The solar system consists of the sun, a star, and bodies that are in orbit around it. These bodies include planets and their moons, asteroids, comets, the Kuiper belt, and the Oort cloud.
Important Terms and Ideas: stars, fusion; asteroid belt; Kuiper belt; Oort Cloud; star types, temperatures, color
Earth’s Movements and Position in the Solar System
The Earth-sun relationship is the key to understanding seasonal changes on earth. The seasons are a result of the tilt of the Earth’s axis and the revolution of the Earth around the sun. Long-term changes in the sun and in the Earth’s orbit affect the Earth’s climate over geologic time. The spin, or revolution, of the Earth causes daily changes. The moon causes tides and other effects on Earth.
Important Terms and Ideas: axial tilt, effect on the strength of sunlight; seasonal changes, length of day, temperature; phases of the moon, tides
In addition to assessing your content knowledge, the questions on the HiSET® Science test may involve facility with the processes of science. The following categories of science processes and the specific skills listed under each are likely to appear in test questions.
Science is a process of discovering and documenting how the world works. Interpretation of data and application of principles of reasoning and of established knowledge are central to this process.
Scientific study involves the gathering of data from experiments and/or observations. These data are then interpreted to find patterns or determine the answer to a specific question. All observations and interpretations must be presented for others to review and attempt to duplicate.
A scientific investigation usually starts with a question or problem and a hypothesis suggesting a possible answer. The hypothesis is then tested by experimentation or systematic observations. Using principles of reasoning, a conclusion is made from these observations. These data and conclusions are presented in a final report for others to verify.
Important Terms and Ideas: hypothesis; experimental design, control; inductive and deductive reasoning
Scientific data often must be analyzed, usually with statistical methods. In general, analysis refers to the breaking down or picking apart of a topic into its constituent pieces in an attempt to understand the topic better.
Research questions may come from unanswered questions, new findings, or unexpected findings of previous research. They may also start with an observation of a real-world phenomenon and a desire to understand what caused it and/or what effects it might have.
The question and hypothesis may suggest certain procedures that will best lead to definitive answers. Very often the procedure will require steps to account for or eliminate the effects of certain variables on the result. Usually, several variables or conditions influence any phenomenon and procedures must be designed to eliminate or account for the effects of all but one of them, the subject of the research question. For example, some aspect of health may be affected by a person’s weight and age. To understand the effects of one of these factors, your procedure must eliminate or account for the effects of the other factor.
Any procedure is limited in how well it provides relevant information for a research question. Often, this involves precision and accuracy of measurements. For example, if a certain procedure is accurate to 1 centimeter, but your question/hypothesis requires seeing differences of 1 millimeter, the procedure will not work for that investigation.
Important Terms and Ideas: accuracy; precision; units of measurement; variation, standard deviation; mean, median, mode
The best procedure will be determined by the need to control all but one possible variable affecting an outcome, and the analytical tools that will provide the needed accuracy and precision.
Important Terms and Ideas: identifying relevant variables to measure or control
When the results are obtained, they must be evaluated or judged. Are they accurate? Do they reflect an unbiased approach? Do they support the hypothesis? Then the results can be examined to determine if they can be generalized beyond the specific study or experiment. For example, if the study was performed on men, do the results generalize to women or to anyone of a different age?
An experiment or scientific study can usually be broken down into the following components:
The hypothesis is a suggested answer to a research question. The hypothesis must be formulated in a way that suggests a way to test it or allows for it to be tested.
All investigations and investigators will have assumptions. In science, these assumptions must be made clear to anyone reading the report and it must be clear that the assumptions have not biased the procedure and/or results in any way.
All data used in making conclusions must be presented. Also, the techniques or procedures used to obtain the data must be documented and presented so that other investigators can attempt to replicate the results.
All reasoning for the conclusions must be presented. A thorough discussion of the results should also include possible alternative conclusions and why they are not supported as well as the conclusion that is offered.
A scientific report should include a discussion of the relevance of the particular question to a broader area of study. Does it support previous findings or suggest revisions to existing knowledge? Is it possibly extendable to other areas?
All scientific reports will include sources for the information presented. The standard of reliability is to use studies published in peer-reviewed journals. Private communications are allowed, but the source must be named.
Important Terms and Ideas: peer review process